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Category : PhysicsPowerUsers.info - Paul Doherty Askme Archive of Questions and Answers
QAId : 345107
Asker : deckcmo@...
Subject : Rotation of the earth
Private : No
Question : What causes the earth to rotate around the sun, and what determines
the speed of it's rotation around it's axis?
Answer : The sun's gravitational field has un trapped in perpetual "freefall"
similar to satellites in orbit around the Earth (or our natural satellite, the
moon). The Earth is in orbit around the sun and moves a horizontal distance
(perpendicular to the sun) equal to how far it would have "fallen towards" the
sun in the same time period had it been stationary. That is why we stay in orbit
and do not either move closer and burn up, or move farther away and escape the
solar system.
As for the Earth's spin I'm not sure why it began spinning but here are some
resources that go into some detail on the spin itself (though they don't know
why either - some venture some theories).
http://image.gsfc.nasa.gov/poetry/ask/q727.html
http://image.gsfc.nasa.gov/poetry/ask/arot.html
http://imagine.gsfc.nasa.gov/docs/ask_astro/answers/970401c.html
Paul Doherty
Rating : 3
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QAId : 345181
Asker : prakash_sankar
Subject : Physics
Private : No
Question : How do we see the different colors during sunrise and sunset?
Does air impurities and reflections play any part in the different colors of
sunset and sunrise we see?
Answer : It's not "impurities" - it's air. Light in the uppper range of vision
(blue and ultraviolet) interact with the air and are re-emitted like all
frequencies as they pass through a medium but blue and ultraviolet interact more
and are "scattered" more than the other frequencies, making our sky blue, and
making the sun at it's zenith (overhead) appear more towards yellow (white light
minue some blue). At sunset and dawn the sun's light is now travelling through
the maximum of air possible and has even more blue removed than normal tinging
the sun the familiar orange-red we all have seen. Particulate matter/pollution
may intensify this effect but is not primarily responsible for it.
Paul Doherty
Rating : 5
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QAId : 345388
Asker : Anonymous
Subject : Physics
Private : No
Question : How does a nucleous of an atom split?
Answer : It's not just any old atom that can be "split" - and that's really a
misnomer anyway as we don't do the splitting - the atom does so spontaneously
under the right circumstances. Uranium is used for this purpose as it is a
cumbersome atom being one of the most massive in terms of the number of nucleons
present in it.
The nucleus, as you may or may not know, is composed of neutrons (negative
charge) and protons (positive charge). When referring to a nucleus the protons
and neutrons are collectively referred to as nucleons. A nucleon in isolation
has a constant mass, or amount of material that makes it up. What is interesting
is that this mass is *not* always a constant amount. What do I mean? Well for
example, a hydrogen atom is the simplest element, consisting of a single proton
in the nucleus and one electron in orbit. Let's say this proton has a mass of
'X'. In a hydrogen atom this is the maximum mass a proton can ever have. When
more than one proton or neutron share a nucleus there is a strong nuclear force
that bonds them together and that actually *reduces the mass of each element
thus bonded.* If you were to measure the mass of a proton outside a nucleus you
would find it at full mass. If you then measured it's mass inside a nucleus
consisting of the proton and a neutron you would find some of the mass 'gone' in
the form of the nuclear bonding force holding the two together. This is
important to understand - I will now be using a term "mass-per-nucleon" which is
an indication of the average retained mass (from it's normal full-mass state) of
each element of the nucleus in different elements. It's a way to compare the
loss of mass between differing elements (thus between differing atomic
configurations). Once more than one nucleon is present in the nucleus the mass
per nucleon starts to fall very quickly. The quickest change comes from hydrogen
to helium since this is the very first introduction of a more mass-decreasing
nucleons. As we move along the scale of atomic complexity (adding more protons
and neutrons as we go) the mass-per-nucleon continues to drop as denser
symmetrical nucleuses are formed. After one of the most stable and dense
nucleuses, iron, however, something starts to happen. The atoms more complex
(heavier) than iron start to reverse this trend, increasing in mass-per-nucleon.
This is due to lack of symmetry in these denser atoms - some nucleons are not
bound on as many sides as in the less-dense atoms thus increasing their mass
(since the nuclear bonding force does not act as strongly when they are farther
from neighboring nucleons - thus they lose less mass). When you get to an atom
like uranium you have a highly unstable configuration which results in a high
mass-per-nulceon. When uranium or plutonium absorbs a neutron they become
unstable and electrical respulsion of the large number of protons overcomes the
nuclear bonding force and the atom splits into fragments. The energy of a
nuclear bomb or of a nuclear reactor comes from the fact that *the total
mass-per-nucleon of the resulting fragments is less (since the fragments are
more stable nucleuses and thus have more symmetrical layouts) than the
mass-per-nucleon of the same number of protons and neutrons before the atom
split* - this difference is the energy given off in kinetic (the fragments
ejected during the splitting) and radioactive form.
Paul Doherty
Answer : Don't forget to rate the answers you receive on AskMe.com
Rating : 5
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QAId : 345459
Asker : djshewan47419
Subject : cold fusion
Private : No
Question : How close, or indeed how far are we from cracking cold fusion. Have
there been any real advances? if so what are they?
Answer : It is unlikely we will find a way to perform cold fusion - the
respulsive forces on two hydrogen atoms (being composed of one proton each) are
too great to get them to meld without high temperatures (which require massive
energy on our part). The sun is a standard fusion reactor, constantly fusing
hydrogen atoms into helium atoms with high temperatures. If we can get a fusion
scheme that can put outmore energy than it takes to run then we will have broken
past the "break-even" point and our energy worries will be over. But I would
expect it to happen in a "cold" manner - expect heat, and lots of it.
Paul Doherty
Answer : Fingers moving slower than my brain - that last sentence should read
"wouldn't expect" not "would expect"
End :
Rating : 1
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QAId : 345522
Asker : w8hz
Subject : Sound of tree falling
Private : No
Question : This is an old rhetorical question but I think it is still
interesting:
If a tree falls in a forest and there is no one there to hear it, does it's
falling make a noise.
Thank you,
Bob ...
Answer : This is a great old question that simply revolves around whether one
defines "sound" as:
1) A mechanical vibration through a conductive medium (air, water, etc).
OR
2) A psychological response to a medium vibration, requiring an organism
equipped with vibratory-detection senses be present to experience it.
Paul Doherty
Rating : 3.1
End :
Rating : 3.1
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QAId : 375465
Asker : wlseese04946
Subject : heat conduction
Private : No
Question : What can you tell me about heat conduction? I am doing a lesson for
sixth graders. Where can I find more information on it on the Internet?
Answer : Heat conduction is one of three methods for the exchange of heat, the
other two being convection (involving circulating fluids) and radiation
(electromagnetic energy (light)).
Convection occurs when materials that are good heat conductors touch. The
thermal energy (high molecular movement average) is transferred by both impact
(for all materials to some degree) and by the movement of free electrons in
metals (which is why they conduct heat and electricity so well).
Here are some links to info you may like:
http://www.ronkurtus.com/physcien/heat.htm
http://physics.mtsu.edu/~plee/SCI_OUTREACH/heat1u.txt
http://www.jhu.edu/virtlab/heat/cond_des.htm
http://www.madsci.org/posts/archives/feb98/885153825.Ph.r.html
Paul Doherty
Rating : 3
Rating : 3
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QAId : 385040
Asker : Anonymous
Subject : speed light
Private : No
Question : How many times greater is the speed of red light(wavelenght=700nm)
than the speed of blue light(wavelength=400nm)in a vacuum?
Answer : The speeds are the same - all electromagnetic radiation travels the
same speed. If it didn't paintings would look horrible :-)
The wavelength is different for red and blue light as you indicated (blue being
a shorted wavelength) but the piece missing from your question is that red and
blue *also* have differing frequencies of oscillation. The blue light oscillates
*faster* than red light does with the end result being that the same *distance*
is covered by both (since the distance is the product of wavelength times
frequency). Here is an illustration of the concept:
RED_LONG_WAVELENGTH X small_frequency
blue_short_wavelength X HIGH_FREQUENCY
Paul Doherty
Rating : 4.9
Rating : 4.9
Rating : 4.9
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QAId : 386688
Asker : er1n2006
Subject : nuclear fusion
Private : Yes
Question : I am in 6th grade. I am researching nuclear fusion and want to know
when it will be available as a viable energy source.
Thank you for your help
Answer : Fusion reactions are when nuclei are slammed together to form a new,
more dense nucleus. The trouble with this procedure is that the contents of each
nucleus is at least one proton which has a positive electrical charge. Like
charges repel each other so the two nucleuses are like the same sides of two
magnets, pushing away from each other and the force gets much stronger as they
get closer together. The normal method to get around this repulsive force is to
generate lots of heat. Heat is nothing more than motion (kinetic energy) and if
the nucleuses are made to move fast enough they can overcome their repulsion and
be pushed against one another and form a new nucleus, giving off energy in the
process. So our problem is three-fold: 1) generate enough heat to cause this to
happen - we already can generate the heat to cause this 2) keep the
heat/reaction going - this we cannot do and 3) get more energy out of the
reaction than we had to put into it to start the fusion process - this also we
cannot do.
If we can find a way to make the reactions happen without requiring lots of heat
(the current situation) then we may see fusion reactors in our lifetime. With
heat only it may take longer...
Here is a web page you might like about fusion:
http://stuweb.ee.mtu.edu/~kklafran/EE280.html
Paul Doherty
Rating : 3
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QAId : 391211
Asker : Anonymous
Subject : sound
Private : No
Question : The intensity of a 67 dB sound doubles and then increases by a factor
of 10. What is the corresponding change in dB?
Answer : Well doubling the loudness brings thr 67db sound to 70db. And then
increasing it by a factor of 10 adds 10db to a total of 80db.
Paul Doherty
Rating : 5
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QAId : 412933
Asker : grail
Subject : theoretical question
Private : No
Question : Don't think that this is just a goof off question, if water going
down a drain goes counter clockwise in the northern hemisphere and the opposite
in the southern, then what if you could, for the sake of argument, put half the
drain in the northern hemisphere and the other half in the southern, what
direction would it flow? I'm not crazy, I've always wondered this since I was a
child.
Answer : The question isn't all that silly but is quite difficult (and useless)
to answer. The reason it's kind of useless is the drain circling thing only
occurs with *perfectly* still water with no disturbances whatsoever. Any
disturbance is enough to easily overwhelm this (IIRC) "coriolis effect" and make
the water drain in the opposite direction.
Force to answer the question when the water holder is arranged half norther,
half southern I'd have to say that this is analogous to standing a coin on end
and guessing which way it will fall. the forces are supposedly *balanced* but in
fact are not, and the side on which the balance of torque falls, so falls the
coin.
Paul Doherty
Rating : 4
Rating : 4
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QAId : 513030
Asker : Anonymous
Subject : nuclear fusion
Private : No
Question : what are the mechanics of generating this energy?
what are the costs of this energy?
what are the environmental considerations?
what are the advantages and disadvantages of this enegy?
what are the practical applications?
what is some other useful and unique information that you think is important?
Answer : To understand where we get the energy from, read this answer I gave on
fission as the concept of where the energy comes from is identical in both
fission and fusion. The only difference is that with fusion you bond two light
nuclei into a third, denser one, and in fission you "split" a large nucleus into
smaller elements.
http://www.askme.com/ViewAnswer.asp?vid=345388
Environmental considerations are better with fusion than with fission. The
by-product of fission is radioactive materials - the by-product of one type of
fusion (hydrogen atoms), however, is helium.
Some of the advantages are obvious - less pollution and almost infinite energy
since, unlike uranium, hydrogen is one of the most plentiful elements in the
universe.
Paul Doherty
Answer : Don't forget to rate the answers you receive on AskMe.com
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QAId : 542147
Asker : lindo13149526
Subject : bounce
Private : No
Question : What is the relationship between the bounce of a basket ball and its
air pressure?
Answer : I would think there would be a linear relationship (up to the point
that the rubber's elasiticy is reached) from low to high pressure and low to
high (potential) bounces.
With too little air inside the ball you get almost none of the rubber's
elasticity as the ball weighs nearly the same with this low pressure and there
is so much "mush" to the impact (time over which the force acts is LONG) that
there is little chance of bounce. Once the pressure comes up to where the ball
is taut both the rubber's properties *and* the air pressure inside combine to
result in a bounce. Increase the air pressure more and the bounce is more
pronounced until you reach the limit of elasticity (or you blow the ball apart
with air pressure :-).
Paul Doherty
Answer : Don't forget to rate the answers you receive on AskMe.com
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QAId : 567992
Asker : neon_genesis_evangeo
Subject : Bouncing of Tennis Balls
Private : No
Question : I was wondering why cooler tennis balls don't rebound as well as
warmer tennis balls. Is it because of the atoms' lattice? Why? Thanks for taking
time answering these questions. Keep answering those questions - we appreciate
it. =)
Answer : I would imagine that it is simpler than that - it's more likely the
reduced air pressure associated with the less-active (cooler) air inside the
tennis ball not contributing as much to the rebound. Certainly if made cool
enough the rubber's elastic properties can be reduced.
Thanks for the kind words!
Paul Doherty
Answer : Don't forget to rate the answers you receive on AskMe.com
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QAId : 617741
Asker : cookiefighter13
Subject : cathode ray tube
Private : No
Question : In the television or computer, the cathode ray tube is the object
that produces the light and images on the screen. The colors emitted are red,
blue, and green. Why aren't they primary colors(red, blue, yellow) instead?
please send your answer to
cookiefighter13@yahoo.com
Answer : I think maybe you're confusing paints with light. The primary colors of
light *are* red, green and blue. The difference between the primary colors
between paints (or inks) and light comes from the way the color is perceived.
Light is additive - when more frequencies get added they "accumulate" for lack
of a better word, culminating in the familiar white light which is all visible
frequencies.
Paint is subtractive (in fact all objects we see are subtractive in the nature
of how we perceive them). A red shirt is red because it absorbs all frequencies
of light *but* red, as opposed to a neon sign (not the generic term, but actual
neon - which glows red) which glows red because red is the *only frequecy being
produced*. If you add in all the colors of paint to a canvas what do you get?
You get black since you are no absorbing all the colors present in white light,
leaving nothing left. This is also why black pavement gets hotter than a tan or
white sidewalk - the black pavement absorbs the majority of the light striking
it, while the lighter-colored materials reflect (in a fashion) the majority that
strike them.
Paul Doherty
Rating : 5
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QAId : 623836
Asker : Brendar
Subject : atmospheric pressure
Private : No
Question : Are atmospheric and absolute pressures the same type of pressure?
Answer : Atmospheric pressure is pressure derived froim the weight of air
molecules surrounding and above us. The only references I found to absolute
pressure are related to scuba diving. Absolute pressure in this context is the
combination of both atmospheric pressure *and* the water pressure (which being a
fluid also increases as the amount above you increases).
Paul Doherty
Rating : 3
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QAId : 640964
Asker : i_got_email
Subject : neutrino
Private : No
Question : what exactly is neutrino? One property of its properties is that it
interacts weakly with matter and is very difficult to detect. How does
neutrino's weak interaction with matter affect the detection of its existence?
Answer : I am not really up on neutrinos so I will suggest a few web sites I
found:
http://whyfiles.news.wisc.edu/004antarctic/
http://budoe.bu.edu/~superk/times.html
http://cupp.oulu.fi/neutrino/
Paul Doherty
Rating : 2
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QAId : 642636
Asker : saville@...
Subject : formula.
Private : No
Question : 91.4-((91.4-t)*(.478+(301*sqrt(v))-.02*v)) represents a formula that
I believe is the velocity of an object falls. ie a skydiver.But I am not sure.
Thank you for any help with this.
Gavin
Answer : I don't answer math-based physics questions but on this one it appears
you have made it too complex.
IIRC velocity of fall (neglecting terminal velocity and air resistance in
general) is:
gt
Distance fallen is:
1/2gt^2
And if you have some way to calculate the surface area of a skydiver you can
figure out at which velocity terminal velocity kicks in and acceleration stops.
Paul Doherty
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QAId : 673705
Asker : Anonymous
Subject : science careers
Private : No
Question : I am wondering how a computer service technition relate to the field
of science.
Answer : Well when you get down to brass tacks "science" is nothing more than a
rigorous adherence to observation and past experience. So in that sense a
computer technician employs scientific techniques all the time. For instance,
when troubleshooting a problem with a system, a series of mini-experiments is
conducted, to rule out which subcomponent or subsystem may be at fault. by
knowing what functions apply to which areas, and by knowing how to test for
functionality in each area you can isolate the faulty portion of the whole.
Paul Doherty
Answer : Don't forget to rate the answers you receive on AskMe.com
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QAId : 675613
Asker : Anonymous
Subject : freefall
Private : No
Question : I have to do a research paper, on freefall, to graduate. Can you give
me some imformation?
Answer : Freefall is pretty straightforward - it's just what happens to an
object when it's freely subjected to a gravitational field. What happens is the
full force of the gravitational field goes to accelerating the object towards
the body providing said gravitational field. In the absence of an atmosphere
this acceleration would continue (and get more intense as the proximity between
the bodies closes) until the object smacks the surface. On our planet, however,
air resistance is a factor with any fall lasting more than 10 seconds or so.
Once the object has fallen this long air resistance builds up until it equals
the weight (at that altitude) of the object - at which point no further
acceleration takes place. This state of equilibrium is called "terminal
velocity" and is the fastest the object can fall unaided (like unless you strap
a rocket on it and face the rocket down :-)
Paul Doherty
Rating : 5
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QAId : 680132
Asker : scapp
Subject : Airplanes....
Private : No
Question : When you're on a plane with a drink, and the plane banks to make a
turn, the liquid level in the cup barely moves even thought you're almost
sideways. I know it has something to do with the pressurized cabin, but what is
the point where the liquid will actually spill out if the cup? Or will it never
spill?
Answer : The effect you're describing isn't due to the pressure in the cabin.
It's due to the fact that even during a turn you have a huge momentum in the
forward direction. Think about the plane like it's a large roller-coaster. When
it heads into a corner it doesn't stay level with the ground - it banks around a
corner at an angle to the ground so part of the forward momentum is experienced
as "additional" gravity, like G-forces in a fighter plane. You would have to
have a severe bank to get your drink to spill due to this additional force. A
good way to understand it is to picture the difference between your drink
sitting on the tray table with the plane at rest on the ground and using a crane
to tilt the angle of the plane (it would spill when it would anywhere else on
the ground - the liquid acting as a natural "level") and the dynamic situation
that occurs when the plane is at the same angle of tilt but in forward motion
and in a banked *turn*, not just tilted.
Another way to think of it is that a plane in a banked turn is becoming very
similar (depending on the angle of the bank) to a rock tied to a string that is
being swung around in a circle. The force that holds the rock in the circular
path is communicated by the string (and provided by your arm). The force felt by
the rock is that of the fake force, centrifugal force, which is nothing more
than the tendency of the rock's momentum to carry it in a straight line.
In answer to your spilling question - yes the cup will spill, but at an
increased angle compared to the same cup at rest on the ground.
Paul Doherty
Rating : 5
End :
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QAId : 691306
Asker : atorres947955
Subject : refraction and reflection
Private : No
Question : What is refraction? What is reflection? What is the difference
between them?
Answer : A reflection is when a lightwave strikes a surface and in deflected
back away from the surface. The most common example is a mirror. If you aim a
light source at a mirror 20 degrees off-center to the left the light will be
reflected at 20 degree angle to the right of center.
A refraction is the change in path associated with light *passing through* a
transparent medium of some kind. This is caused by the slower speed of travel
for light that passes through denser mediums like water or glass. While the
instantaneous speed of light is a constant there is an absorbtion/re-emission
process as light passes through that makes the end result of light taking longer
to pass through (approx 75% the speed in a vacuum for light travel through
water; 99% for light through air). A good example of refraction is looking into
a swimming pool or bathtub and seeing the person's extremities being distorted
or in the wrong position. The light is actually taking the shortest-time path
through the medium which seems kind of odd, but it does. What this means, since
light travels slower through denser mediums, and the fact that our brains
perceive light as traveling only in a straight line, is that we see objects
immerse in water at a higher height than they really are. Imagine a fish
floating in the water at a short distance away and you are looking into the
water at the fish, gauging his depth in the water. The light leaving the fish
that strikes your eye takes the least-time path to your eye as I mentioned. What
this means in practice is that the light wave is bent slightly towards the
perpendicular (meaning it bends towards vertical) before striking the air at the
water/air boundary. It's helpful to think of a lightwave as a small flat plane
perpendicular to the direction of light travel - an easy way to picture this is
to imagine a lawnmower at the forefront of the lightwave, that is being pushed
froward by them lightwave. When the lightwave begins to enter the air it speeds
up but because it's traveling at an angle the side of the lawnmower that enters
the air first (the side closest to the vertical line) speeds up first, bending
the direction of travel for the whole lightwave. This results in the shortest
amount of *time* (not necessarily distance) of travel for the lightwave, but
results in your seeing the source of the fish's light as coming from a direct
line-of-sight location from after that last bend when the light emerged from the
water. The spot you see the fish is actually higher than where the fish is
located.
Paul Doherty
Rating : 5
Rating : 5
Rating : 5
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QAId : 693708
Asker : thebigcor
Subject : hi
Private : Yes
Question : okay here goes i lost a wallet weeks ago either i dropped it outside
my car in front of my place ..or i lost it in my house, or someone took it out
of my car.. what do you see about this.. also i want to know what you see as far
as me selling this jeep wagoneer i have that i had to repay a buyer back and
than i fixed it with all my money will i sell it asap. i hop.. hey hows my love
life look i hope something happens soon.. corey 12/10/65
Answer : I think you've confused the word "physics" with "psychics" - I feel no
vibrations in your general direction, perhaps a 1-900 number can help? :-)
Paul Doherty
Rating : 5
End :
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QAId : 721665
Asker : lazb0y
Subject : Nuclear Fusion
Private : No
Question : Hiya I have a large essay to do on Nuclear Fusion and I am doing
research at the moment.I was wondering if you could offer ANY information or
literature on the subject.
Thanx
Answer : Sure thing - just open the URL below, which is answer I gave on the
same topic (it in turn references another one I answered on fission and fusion).
http://www.askme.com/ViewAnswer.asp?vid=513030
Paul Doherty
Answer : Don't forget to rate the answers you receive on AskMe.com
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QAId : 735870
Asker : Anonymous
Subject : electricity
Private : No
Question : Explain why I am more likely to get a shock by walking across a
carpet in Jan. than in Jun (at least in mid-west area) Where might the opposite
be true?
Answer : Your liklihood of being shocked across a carpet has to do with the
amount of moisture in the air. The less humid it is (the less moisture in the
air there is) the more likely you are to carry a voltage differential along with
you. The more moisture in the air (higher humidity) the faster the charge you
produce will "leak off" into the air, making it less likely for you to receive a
shock. It's usually less humid (and there is a lower cap on relative humidity)
in January when it's cold than in June when it's relatively warm. Relative
humidity is the measure of what percent of the air contains water vapor as
compared to the maximum amount that *could* be in the air *at that temperature*.
So somewhere where the humidity is almost always high is a place you would be
less likely to get shocks.
Paul Doherty
Rating : 4.9
Rating : 4.9
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QAId : 745512
Asker : emeraldinmay@...
Subject : reflection
Private : No
Question : what is reflection? what is a good experiment to demonstrate
reflection? (i am 11). thank you.
Answer : A mirror is the most common, and easiest to see, example of reflection.
Ask your Mom for a pocket mirror or hand mirror and hold it up to your face. The
image you see is the result of the reflection of light rays leaving your face
and bouncing off the mirror into your eyes. A surface becomes a mirror if the
irregularities (present in all materials at some level) are small enough to be
"invisible" to the wavelength of light that strikes it. In other words a mirror
is just a mirror because it's smooth enough to not randomly scatter the light
that strikes it, but rather uniformly deflects it.
Here's another question I answered on reflection and refraction that you might
want to read with your parents:
http://www.askme.com/ViewAnswer.asp?vid=691306
Paul Doherty
Answer : Don't forget to rate the answers you receive on AskMe.com
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QAId : 761103
Asker : acyran84929
Subject : static
Private : No
Question : How does the use of fabric softener in the dryer prevent static
cling?
Answer : I found just the site for you:
http://www.pg.com/schldays/fabric/24101.htm
Paul Doherty
Answer : Don't forget to rate the answers you receive on AskMe.com
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QAId : 803664
Asker : Tatencio09457
Subject : Quantum physics
Private : Yes
Question : Hello,
I have always avoided math and science. However, quantum physics intrigues me.
Will you tell me the basics of it, and do you think time travel is possible, or
"warp" travel? I'm not a dope - my forte' is art and music! Thank you for your
time.
Answer : You asked a mouthful... one of the main precepts of quantum mechanics
that differs from traditional physics is the concept of uncertainty. Where
traditional physics makes an underlying assumption that all events can
eventually be dissected into their constituent parts, quantum physics has no
such illusions. The main idea that illustrates this dichotomy is that of
Heinsenberg's Uncertainty Principle. This principle is perfect for this
discussion because it shows that, even in theory, it is not possible to know all
the factors one would need to know to predict sub-atomic collisions. In
macroscopic physics, for example, if you were going to throw a tennis ball at a
wall and could gather enough information in advance about the pull of gravity,
the arc and initial velocity of the tennis ball, the elasticity of the ball and
the wall as the ball strikes the wall, the friction of the ball as it strikes
the ground and rolls, and so on, you can predict with great certainty where the
ball will end up and the course it wall take on it's journey. We would like to
be able to apply those same rules of momentum and trajectory in predicting
subatomic collisions. Unfortunately the same can not be said of the predictive
ability of physics at this level. The reasons have to do with the nature of
viewing an event and with the sizes of the objects involved. When we view an
event in the macroscopic world we make almost no impact on the objects being
viewed, such that we tend to ignore the fact that our mere presence does have an
effect on the outcome of the event being measured. In the subatomic realm our
observational impact cannot be ignored and has a serious impact on the results
of the very thing we are measuring.
An example of a thing we would like to be able to apply our predictions to, and
be able to measure, would be the collision of two or more subatomic particles
like electrons. Why can't we just get the same information about it that we got
about the tennis ball and go from there? The two main pieces of information we
need about the electron to predict what will happen to it when it collides are
it's velocity and direction of travel. We knew both of these to a good precision
about the tennis ball before it's collision which is what enabled us to be
highly accurate in our prediction. The problem comes in when you try to
determine both of these items for an object that is as small as an electron. The
first problem is even seeing an electron, given the miniscule diameter of one.
What we have to do to see an object as small as an electron is to move upwards
in the electromagnetic spectrum. Whereas we could use visible light to view the
tennis ball before, during, and after the collision we cannot use those
wavelengths to view an electron since the wavelengths of visible light are far
too large to reveal an object so small as an electron. The visible light
frequencies would be like a semi truck that strikes a butterfly in flight -
unaffected and unaware that anything has taken place. The visible light
frequencies are too "coarse" to reveal such a tiny diameter object. So what do
we do then? We start shortening the wavelength in a search for one short enough
to reveal our electron. The problem is that as you move higher into the
electromagnetic spectrum each successively shorter wavelength carries with it a
higher energy per photon (a photon is a "packet of light" - the smallest unit of
light emitted at one time from a electromagnetic source). For example you don;t
wear sunscreen inside your home do you? That's because the visible light
frequencies produced by the incandescent or flourescent bulbs in your home do
not have enough energey per-photon (they are relatively long-wavelength
radiation with a short frequency) to harm your skin. But outside where the sun's
rays leak through the atmosphere a lot of ultraviolet gets in (which is a
shorter wavelength than the shortest visible wavelengths of blue light) and it
contains enough energy per photon to do damage to your skin. So the same way the
shorter-wavelength, higher-energy ultraviolet light can damage your skin the
higher we go in search of a frequency to reveal the electron the more energy per
photon we will be imparting to the objects we attempt to view. By the time we
dial up to a wavelength short enough to "see" an electron so we can pinpoint one
of our items of interest, it's exact location, we are in the neighborhood of
gamma radiation and are imparting a huge amount of energy per photon. When we
use this frequency to find our electron we can know it's exact position which is
one of the things we need to know to predict it's impending collision. The
problem comes from the massive energy per photon and the fact that electrons
have very little mass. We now have pinpointed the electrons position to a good
level of accuracy but now, in using such a high-powered radiation to illuminate
it's position, we impart so much energy to it (and due to it's small mass) we
send it flying off in an unpredictable direction so we now know nothing about
it's velocity. That's bad so now we dial down our wavelength to one that can
show us the velocity of an electron but doesn't impart enough energy to send it
careening. Know we know what direction it's heading with good precision but
we're back to our original problem - we don't have fine enough resolution to
pinpoint it's location!
So what this boils down to is that we can know *either* the position or the
velocity of the electron at any given time but not both at the same time, which
means we cannot apply the same types of predictions to it, even in theory, as we
did to the tennis ball.
Paul Doherty
Answer : I forgot to answer the warp travel question...
I don't have any information about time or warp travel, other than to have heard
of supposed faster than light travel particles I believe are called "tachyons".
Paul Doherty
Answer : I typo'd on the name of the founder of the Uncertainty Principle - it's
Heisenberg.
Rating : 5
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QAId : 812313
Asker : scdoom13
Subject : air and ice
Private : No
Question : I am a seventh grade student and I would like to know why when air
gets cold it contracts but when water ets cold it expands. Such as when a
balloon is cold it shrinks but if you fill i water bootle up to the top and
freeze it it will expand and maybe pop the bottle. Why is that?
Answer : A very astute observation. Most people don;t notice this strange
inconsistent behavior of water. Considering that for almost all other materials
the order of least to most dense is gas, liquid, soild, it stands to reason that
water is odd for the fact that the solid form (ice) floats on top of the liquid
form, and indeed forms on the top of the water first!
Water behaves in this strange way due a unique crystalline structure that water
undergoes when freezing (becoming a solid). The open hexagonal structure
actually takes up *more* space in this form than the same quantity of water in
liquid stage. The end result is that the ice is of a lower density (less
material per unit of volume) and thus is "lighter" than the same volume of water
and floats. As to why it freezes on the top of the water as water is chilled
from warmer temperatures it does indeed become less energetic and more dense.
This continues down to about 4 degrees Celsius, just above freezing. At this
point ice is at it's maximum density and this 4-degree water sinks to the bottom
of whatever container is present (lake, sea, ice cube tray, etc) and warmer
water moves in to take it's place. Cooler than 4 degrees C is where the
crystalline structure begins to form which makes the water less dense as it
moves towards freezing. Only after ALL the water in the container has been
coooled to 4 degrees Celsius can further cooling take place. The most commong
example of this is a lake whose top freezes over for ice skating in the winter.
The whole body of water was at 4 degrees C before freezing from the top down
(where the colder air cooled it). This also explains why the oceans don't
usually freeze at all even during the coldest winters. They don't stay cold
enough long enough for the entire depth to reach 4 degrees Celsius. And this
answers the age-old question of:
What temperature was it at the bottom of the ocean on December 2nd, 1961 at 2:24
AM?
Answer - 4 degrees Celsius... because it always is.
Paul Doherty
Rating : 5
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QAId : 817264
Asker : irod7895954
Subject : special theory of relativity
Private : No
Question : in what decade did einstien come up with this theory?
Answer : It was in the firstd decade of the twentieth century (1905):
http://sci.hkbu.edu.hk/math/einstein.html
Paul Doherty
Answer : Don't forget to rate the answers you receive on AskMe.com
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QAId : 832634
Asker : bec72
Subject : clouds
Private : Yes
Question : Hi Paul, this is something I often wonder about and occasionally ask
some one in passing (who generally then tell me to get a hobby!!). Maybe you can
help.
A cloud is sort of ball of gas right? Does it have the same weight as it's
elements combined. I mean, if 1 litre of water weighs 1 kg, how the hells does a
cloud float through the sky??
I'm sure it's a simple misunderstanding on my part... hoping you can do an
"idiots version' for me..
Rebecca.
Answer : I guess the area of confusion is that, while a cloud can produce water
in the form of rain or snow, the state of the matter inside the cloud before
rain is in the form of particulate matter (fancy way of saying "really small") -
water vapor and particulate matter. When these elements combine that is
condensation, and is what forms water droplets which then have enough mass to
fall as rain.
I hope that helped a little... and BTW - get a hobby! ;-)
Paul Doherty
Rating : 5
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QAId : 892470
Asker : billly36
Subject : Relativity
Private : No
Question : I know the theory of relativity, but I do not understand why time
would slow down at very high speeds. I have been pondering this for quite some
time..... could you please help me out?
Thanks!
Answer : Physics doesn't dictate the way the universe is - it merely attempts to
describe the way the world is in a way that is predictable and useful.
The reason time slows down near the speed of light is apparently so that the
speed of light remains a constant. That is, even people travelling near the
speed of light, would measure light in their vicinity to be travelling at the
same rate as when they were standing "still" (no such thing really - all the
universe is in constant motion - one of the cornerstones of relativity).
Paul Doherty
End :
Rating : 3
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QAId : 901431
Asker : yciros54555
Subject : Ocean Tide
Private : No
Question : The gravitational force of the Moon attracts the Earth, so there is
ocean tide. But if the ocean tide is due to the attraction of the moon, then the
high tide should always facing the moon, but in actual case, there are two
tides, one on the side of the Earth facing the moon , the other on the opposite
side of the Earth ,away from the Moon. Why? I have this question when I was 10
when my shool teacher told me there are always two high tides. Now I am 43, I
still cannot find an easy answer for this question. Of course I mean an easy
answer is an answer that does not use complicated mathematical theory. Can you
find solve the question for me? Thank you .
Answer : Sure thing - first another question that should come to mind when
thinking about the gravitational influence of the moon causing tides is this:
the sun's pull at even it's great distance is still 180 times stronger than the
moons, yet it's tides are much smaller than the moons. The reason for this
(which also leads to how the moon's tidal forces work) is that the strength of
gravity falls off as the inverse-square of the distance between two bodies. That
is a fancy way of saying that if you have two bodies X distance apart there is a
force of gravity (call it "Y"). If you double the distance between the bodies
there is now only 1/4 the gravitational force. If you make the distance three
times as far apart as the original the power is now 1/9th as strong. And so on.
So with the distance over which the sun's gravitational influcence acts it's
force has been greatly reduced, and the *difference between it's force on either
side of the Earth is negligible, compared to the distance from the sun*. The
moon's gravitational power, with it being so much closer to the Earth, is still
fairly strong when it reaches the near side of the Earth, and this power falls
off fairly significantly (again by the inverse-square law) on the opposite side
of the Earth, making for a large disparity in pulling force on either side of
the Earth. Think of the Earth as a ball of jello - if you pull on all parts of
the jello at once the general shape is maintained. If, however, you pull more on
one side than the other the shape become elongated. The side closest to the
Earth gets pulled the most, with the center of the Earth being pulled less, and
the far side pulled the least (allowing it to bulge ("stay where it is")). These
bulges stay in place and as the Earth rotates underneath these influences we
pass into them and see a corresponding rise in water levels as we pass through
either bulge. The other component here is that you cannot think of the Earth as
stationary relative to the moon. The Earth and moon both rotate about the
"Earth-moon" center of mass. This movement and resulting centripetal
acceleration (on the sides facing both towards and away from the moon) help
account for more of the elongated shape of the Earth. The moon too is elongated
from it's proximity to the Earth and thus has "tidal bulges" too - just no water
to show it as much.
Paul Doherty
Rating : 4
Rating : 4
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QAId : 907080
Asker : TobiasJ13
Subject : Bicycle question
Private : No
Question : Consider the following situation:
Two people are riding identical bicycles down a decline. One person, though, is
considerably heavier than the other. Will they both reach the bottom at the same
time, if they both started from rest at the same time? Also, after reaching a
flat at the end of the decline, will either go farther if no further energy is
inputted?
I've been arguing with my friend who claims I have an advantage going down hills
(though certainly not up) because i'm heavier. I claim we'd both be going the
same speed because of the conservation of energy, but she still insists i'm
wrong. Any light you could shed on this would be a great help. Thanks.
Answer : If we assume frictionless parts on the bike, identical bicycles, and
that your top velocity doesn't approach that where wind resistance becomes a
factor I would agree with you - both of you will travel down the ramp at the
same speed (due to same acceleration from gravity) *but* I believe that the
heavier person will travel a bit farther after level due to his increased
momentum (being mass x velocity). It will take a bit longer for friction to slow
his greater mass.
Paul Doherty
http://members.home.net/iqueue
FUQuestion : Thanks for that answer, but there is one more related question I
have. Since I am heavier, raising the center of gravity of the bike (albeit
slightly), and we generally consider gravity as acting on the system's center of
mass, wouldn't the parallel component of the gravity correspond to an increased
torque on the wheel (due to a larger radius from the axle) and cause me to go
faster?
Rating : 4
Answer : I don't believe so, since your entire weight acts at only two points -
where each tire meets the plane. The only effect your higher center of gravity
would cause is that at steeper inclines you would produce a torque (and fall
forward) sooner than the lower center-of-gravity rider would.
Paul Doherty
http://members.home.net/iqueue
----------------------------------------------------------------------
QAId : 955498
Asker : r_pem32979
Subject : resistance
Private : No
Question : can u plz help explain how resistance in a wire is related to
length....
thankz
reena (:
Answer : Well resistance comes from the fact that work must be done to move
electricity through a wire. The longer the wire the more resistance must be
overcome - think of it as inertia - the electrons in the wire are at "rest" and
you are attempting to coerce them into motion.
Paul Doherty, CNA, CNE, MCP+I, MCSE, B.A.Sc.
http://members.home.net/iqueue
FUQuestion : can u plz send me a more deatailed explaination plz.....could u try
and give me the resources u get this info from is well plz
thankz
reena
Answer : As far as more detailed explanations, examine the web resources below -
the following is a quote from the first:
"The collision of electrons with atoms gives rise to resistance - the material
resists the flow of the electrons and the amount of resistance will depend upon
the nature of the material. Some materials such as metals have low resistance
whilst others, like rubber, have high resistance."
http://io.newi.ac.uk/buckleyc/electric.htm
http://www.sci-ctr.edu.sg/ScienceNet/cat_physical/cat_gen01470.html
http://www.exploratorium.edu/snacks/short_circuit.html
Paul Doherty, CNA, CNE, MCP+I, MCSE, B.A.Sc.
http://members.home.net/iqueue
Answer : This is the other one to rate (in case you couldn't find it)
Paul Doherty, CNA, CNE, MCP+I, MCSE, B.A.Sc.
http://members.home.net/iqueue
Rating : 4.9
Rating : 4.9
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QAId : 977962
Asker : libertylabs
Subject : matter and energy
Private : No
Question : As I understand it, all of the matter that has ever been in the
universe is still here. Is all of the energy that has ever been here, still here
also?
Answer : I would say yes - the old axiom is that matter and energy are never
destroyed - they just change forms. What was once chemical energy becomes heat
(fire) - what was once potential energy becomes light and heat (sun's fusion),
etc... The universe is like a large terrarium(sp?) - self-contained.
Paul Doherty, CNA, CNE, MCP+I, MCSE, B.A.Sc.
http://members.home.net/iqueue
Rating : 5
----------------------------------------------------------------------
QAId : 978321
Asker : Anonymous
Subject : physics help
Private : No
Question : I need some help on these true/false questions. Thank You.
1. In a flowing fluid, the pressure where the fluid is moving slower is higher
than the pressure where the fluid is moving faster?__
2.The upward force exerted by a fluid on an object immersed in it is called the
buoyant pressure?__
3. The buoyant force that keeps a ship afloat is an example of Pascal's
principle?__
4. The brakes in a car work because of Pascal's principle?__
5. A hot pizza contains heat?__
6. You can increase the temperature of a gas by compressing it?__
7. Air at a temperature of 32 degree"F" has a relative humidity of 60%. If the
temperature of the same air increases, the relative humidity increases?__
8. Current is the rate of flow of electric charge?__
9. Voltage can also be called potential?__
10. A potential difference is necessary for current flow?__
Answer : 1 True - this relates to Bernoulli's Principle - it's easier to
understand this if you think of a fluid as having a set amount of enery - it can
use this energy for one of two things - movement or pressure. the more of one
you have, the less of the other you have left. This is how planes get life on
their wings (wind passes faster over the top so there is more pressure below the
wing), and how tornadoes do damage (house blow themselves apart since the static
air inside the house has greater pressure than the high-speed winds outside).
2 True - bouyancy comes from the difference between the pressure on the top
(less since it's not as deep) and the pressure on the bottom of a submerged
object. If the object weighs less than the amount of water it displaces (volume)
it will float (or hover).
3 False - Pascals's principle is that pressure is exerted in all directions in a
fluid. Archimedes principle has to do with bouyant objects like a ship.
http://www.mohawk.net/~viking/physics/arch.html
4 True - the fluid in the brake lines experiences an increase in pressure due to
it being transmitted from the brake pedal to the lines hydraulically. The fluid
exerts the same pressure everywhere through the brake system.
5 False - nothing *contains* heat - heat is merely a measure of the thermal
activity of a substance. An object itself can be hot, but not conatin heat.
6 True (I think) - making a gas take up less space than it previously contained
will result in a higher temperature.
7 False - Relative humidity is a measure of how much water vapor the air *could*
contain *at that temperature*. Hotter air can conatin more moisture than colder
air so taking air at one temp 60% RH and increasing the temperature alone will
decrease the relative humidity since the warmer air can now contain more
moisture.
8 True
9 True
10 True
Paul Doherty, CNA, CNE, MCP+I, MCSE, B.A.Sc.
http://members.home.net/iqueue
Rating : 5
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QAId : 984922
Asker : rtorres
Subject : CUAC-CUAC echo
Private : Yes
Question : I know that the duck sounds (cuac-cuac) do not produce echo sounds,
do they?
If it is true ¿Why?
Thanks a lot
Rubi Torres
Answer : No, it's not true - ducks quacks echo like any other sound. Absent
destructive interference (which would require precisely chosen environments and
source sounds) sound is sound and will reflect equally from an echoing surface.
See the URL below for a more entertaining version of the same information by
Cecil Adams, my hero:
http://www.straightdope.com/classics/a5_071.html
Paul Doherty, CNA, CNE, MCP+I, MCSE, B.A.Sc.
http://members.home.net/iqueue
Rating : 5
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QAId : 985485
Asker : r_pem32979
Subject : superconductivity
Private : No
Question : can u plz superconductivity to me.....include resistance.
thankz
reena (:
Answer : Superconductivity is the effect, whereby a material is cooled to near
absolute zero, resistance in the wire drops to nothing. Some materials have been
discovered (so called high temperatue superconductors) that can reach this state
at warmer temperatures (they are still quite cold relatively-speaking). Japan
has a MagLev train (Magnetic levitation) train that runs on magnetic fields and
uses superconductors. Their newest superconducting tarin will reach 340 MPH! See
the URLs below for more details on superconductivity:
http://library.thinkquest.org/20872/intro.html
http://230nsc1.phy-astr.gsu.edu/hbase/solids/scond.html#c1
Paul Doherty, CNA, CNE, MCP+I, MCSE, B.A.Sc.
http://members.home.net/iqueue
Answer : Please rate the answers you receive on AskMe.com - I would appreciate
your rating these last two on resistance.
Paul Doherty, CNA, CNE, MCP+I, MCSE, B.A.Sc.
http://members.home.net/iqueue
Rating : 5
----------------------------------------------------------------------
QAId : 988804
Asker : Anonymous
Subject : light speed
Private : No
Question : Does light always travel at the same speed?
(According to the most modern theories)
Is matter time? could time exist without time? Are matter and time bound up
endlessly in themselves?
Do you believe that there is a world which exists independent of our minds?
Do the perceptible (sensible) qualities of an object exist outside of the mind?
Answer : Yes light *propagates* always at the same speed - that is the
instantaneous speed of light is a constant. Light, however, can be made to
travel slower like passing through our atmosphere or water.
Matter is time...? I would say if anything motion *of matter* is time. Our
concept of time is heavily wrapped around the concept of motion of physical
objects (planets, stars, electrons, etc).
The world we live in exists independed of our minds - our only contact with the
world we're in now is the input from our senses from which our mind constructs a
replica of reality. Watch the 10:00 news programs and you'll see that some
people's reality-generating abilities differ from ours.
The perceptible qualities do exist as I can build a machine to confirm that what
I perceive it also perceives.
Paul Doherty, CNA, CNE, MCP+I, MCSE, B.A.Sc.
http://members.home.net/iqueue
Rating : 4.6
Rating : 4.6
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QAId : 1010487
Asker : dead_sou24499
Subject : speed from a skid??
Private : No
Question : How do you determine the speed that a vehicle was going from the skid
marks it left behind when it stopped? and what does the coefficient of friction
have to do with it???
Answer : Well I would expect you would need to know the vehicles weight (so you
can calculate it's momentum to find it's starting speed) in addition to the
coefficient of friction - the latter being related to the speed since it
dictates at what rate the speed is bled off by the tires and road (higher the
friction the faster the speed is reduced).
Paul Doherty, CNA, CNE, MCP+I, MCSE, B.A.Sc.
http://members.home.net/iqueue
Rating : 4
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QAId : 1012578
Asker : Anonymous
Subject : drive
Private : No
Question : hi can u tell me the diference between fat32 and fat16 for the file
system. I have fat 32 and I rember being at fat16 but i never changed the system
and no one else uses the pc but me???? Also i have this other porblem last week
i had 1.9 gig of hard drive speace and this past friday it said I had 978mb left
on my c drive which is the main drive. and on that same day i went to the movies
and left my pc on and i checked the drive space and this message came up saying
i was out of disk space???? and i never installed anything for the 2 hours i was
gone?? i checked for virus and nothing came up then i defreamgented my drive.
and I check for errors to. then the next day it was back to 978mb but it goes of
and on it decreased the drive space with me installing nay programs or anything.
Asl is there anyway to restore the pc ot fat16?? also might that be the problem
thank you.
Answer : FAT32 is a newer MS file system that can handle larger disks while
simultaneously using smaller clusters which waste less space than larger
clusters.
Likely if you had a FAT16 and it's not FAT32 (how dod you know this?) someone
ran the FAT32 converter on your PC. It's located in
Start/Programs/Accessories/System Tools/Driver Converter (FAT32).
As far as running out of space one of a coupld of things can be happening:
1) You have lots of small files, which means your reported space available is
not accurate as you near disk full - considering you had 978MB reporting free I
doubt this is it unless the disk is large.
2) You have a misconfigured BIOS that is not properly translating the disk size
for Windows. Windows in turn bases it's disk space estimate on this erroneous
information. To fix this involves changing the settings in the BIOS to AUTO and
LBA but may require a reformat. It's also possible your BIOS can not handle the
full capacity of your disk in which case you need to go to the disk
manufacturer's website and get their disk overlay software (for example
"MaxBlast from Maxtor for their drives) which will do a one-time install to the
disk to provide this ability.
Paul Doherty, CNA, CNE, MCP+I, MCSE, B.A.Sc.
http://members.home.net/iqueue
Paul Doherty, CNA, CNE, MCP+I, MCSE, B.A.Sc.
http://members.home.net/iqueue
Answer : Don't forget to rate the answers you receive on AskMe.com
Rating : 5
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QAId : 1012853
Asker : Anonymous
Subject : Physics help please
Private : Yes
Question : Hi I am currently in a physics 101 class and have a 90 questions - I
have answered all but i am stumped on the following and could desparately use
some assistance - your time is greatly appreciated.
1)When a bar magnet is broke in two down the middle, each piece is a)as magnetic
as the original magnet b)actually stronger than the original magnet c)half as
strong as the original magnet d)no longer magnetic. -- i know d is out.
2)When a magnet is thrust into a coil of wire, the coil tends to a)attract the
magnet as it enters b)repel the magnet as it enters c)both of these d)neither of
these.
3)A wire moving sidewise in a magnetic field has NO induced voltage if a)it is
moving in the direction of the field b)it is moving opposite the direction of
the field c)it is made of copper d)it is moving very fast e)two of these.
4)If a magnet is pushed into a coil, voltage is induced across the coil. If the
same magnet is pushed into a coil with twice the number of loops a) one half as
much voltage is induced b)the same voltage is induced c)twice as much voltage is
induced d)four times as much voltage is induced e)none of these.
5)A variety of sunset colors is evidence for a variety of a)elements in the sun
b)apparent atmospheric thickness c)atmospheric particles d)atmospheric
temperatures e)primary colors.
thank you so much.
Answer : 1) C
2) B (it *resists* the intrusion of the magnet is a better way to say it -
because if you stop progressing there will be no net force on the magnet.
3) Not sure of the visual here but I suspect it would be A & B
4) C
5) B
Paul Doherty, CNA, CNE, MCP+I, MCSE, B.A.Sc.
http://members.home.net/iqueue
Rating : 5
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QAId : 1043483
Asker : SimonB
Subject : Physics in music
Private : No
Question : I have just been asked a question by a student of mine which I don't
know even if its true. Is a middle C on one instrument different to a middle C
on another instrument and if so why?
Thanks in advance
Simon
Answer : A "middle C" refers to the frequency of the sound, so for all
instruments playing on the same clef a middle C is the same. The reason they
don't *sound* the same is that the instruments all differ in their timbre - that
is, each instrument's materials and composition color it's sound to make it
unique.
Paul Doherty
http://members.home.net/iqueue
Rating : 4
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QAId : 1055327
Asker : becca11
Subject : electromagnetic radiation
Private : No
Question : What is electromagnetic radiation?
Answer : It is energy, plain and simple. When an atom becomes excited, by
physical or electrical means, it's electrons become elevated to levels above
their normal orbits. These electrons then drop back to their normal unexcited
state and in the process give off the energy they gained. Since the orbits are
at definite levels apart from each other, and since the electrons cannot reside
between these levels, the energy given off by an electron going through this
de-excitation process is said to be quantized. Quantization in this usage means
that the energy is given off in discrete steps of energy. This excitation and
atomic quantization is where we get some of the things familiar to us. As you
probably already know electromagnetic radiation (I'll call it ER from here on
out) in the ranges that our eyes use is generally called "light". So light is
produced by this same mechanism - electrons get excited up to a
higher-than-normal orbit, and then de-excite, giving off the energy they had
gained in the form of a photon (quantized "piece" of ER).
Here's a good example of the quantization of light. I'm sure you've seen the
so-called neon signs in convenience stores and such? Those signs are an
excellent example of the quantized nature of electron orbits. Those lamps
contain a pure gas - in the case of the bright red ones it's neon. The
particular combination of electron excitation/de-excitation steps available to
the neon atoms is what gives neon it's characteristic red color. Argon is
another gas used in these lights and has a blue color for the same reason. Each
type of gas has it's own characteristic pattern of available electron orbit hops
that give it unique color. Contrast these types of lights with an incandescent
light like in your house or on your car. These use a metal filament which when
heated glows and gives off light. the same process if happening as in the gas
but we get (closer to) pure white light from this type of bulb. Why? It's
because now, instead of the limited nmber of combinations of electron orbit hops
we had with a gas (where atoms are relatively far apart), we have a solid
material with atoms shoved close together. The result being that electrons who
make a hop to higher energy orbit in one atom may very well de-excite into a
nearby atom making the energy patterns closer to infinite which also makes the
frequencies of emitted ER nearly infinite - white light. A flourescent bulb
works like a neon light but produces white light. How is that? It uses mercury
vapor inside the tube, which when a current is passed through excites and gives
off the standard limited number of patterns a gas can produce. But this light
isn't even visible - it's ultraviolet in frequency. the white light actually
comes from the spray coating on the inside of the tube - this solid material
absorbs, and becomes excited by, the UV light and in turn gives off it's own
less-limited pattern of white-ish light.
Paul Doherty, CNA, CNE, MCP+I, MCSE, B.A.Sc.
http://members.home.net/iqueue
Rating : 5
Rating : 5
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QAId : 1061949
Asker : AstroConstant
Subject : 3 Questions
Private : No
Question : 1. Why waves require a medium to travel?
2. Why the electrons move only in one direction not the other? What is the force
responsible for that?
3. What is the fourth dimension?
Please answer all these questions adequately.
Thank You.
Answer : Waves (sound, motion) require a medium because a wave is nothing more
than *a disturbance of a medium*. Without the medium there is nothing to "wave".
Light waves of course do not require a medium but they are not waves in the same
sense (they travel as a wave but interact as a particle, and are energy, not
matter).
I'm not sure what this #2 question is asking. Under what situations are you
saying electrons move in only one direction?
The fourth dimension is commonly understood to be - time.
Paul Doherty
http://members.home.net/iqueue
FUQuestion : I meant that in an atom why all its electrons move in only one
directon all the time? Why don't they change their direction?
Sorry that I couldnot tell You what I exactly meant.
Answer : No problem...
I don't know anything about electrons moving in only one direction - in fact I
don't believe that to be the case. Where did you get this fact? Electrons travel
as waves in the electron orbits and can exist at any point inside their
"electron cloud" at any moment, irregardless of their previously-measured
position. The old model (Bohr's) planetary-style orbits were not completely
descriptive of the motions of electrons, but as it turns out are explained by
the fact that each orbit is a multiple of an electron-wavelength, which also
handily shows why electrons only exist at orbit levels and not between.
Paul Doherty, CNA, CNE, MCP+I, MCSE, B.A.Sc.
http://members.home.net/iqueue
Rating : 5
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QAId : 1063457
Asker : Anonymous
Subject : carbon dioxcide
Private : No
Question : What is the painless to do youself in, suidice
Answer : I hesitate to answer such a loaded question. I hope that you are not
considering such a thing yourself. Please contact me at my email address
bitbucket911@home.com and I can answer the question if all you are is curious,
or we can talk if not.
Paul Doherty, CNA, CNE, MCP+I, MCSE, B.A.Sc.
http://members.home.net/iqueue
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QAId : 1075481
Asker : Rellia
Subject : Hockey
Private : No
Question : How does physics relate to hockey?
Answer : Well, other than research methods, not a lot... ;-)
A couple of things come to mind immediately when thinking of hockey and physics:
regelation
inertia
momentum
I'll briefly discuss each...
Regelation takes place at the boundary between the ice skates and the ice.
Regelation is the process of ice melting under pressure and then immediately
refreezing when the pressure is removed. Here's a little thought experiment:
take a large block of ice and drape a metal wire across it with two large
weights, one on each end of the string. This string will melt the ice
immediately beneath it due to the pressure from the weights. What will happen is
the wire will move down slightly into the ice and the ice (now water) above it's
position will refreeze. this process will continue, with the ice immediately
below melting, only to freeze after the wire passes, until the wire has passed
all the way through th block of ice. And what are you left with? A block of ice
very similar to the one you started with. That process is regelation. Ice skates
cause it too, since they support your body's weight. On such a small amount of
surface area the pressures produced cause regelation to take place. So as the
skater moves across the ice the ice is constantly melting the ice with the
pressure of his skates, with the ice melting behind him. So in actuality you
aren't skating on ice at all - but rather a thin layer of water on top of ice!
This is the reason those ice-surfacing machines are used as frequently as they
are - the ice is deformed by the constant melting/re-freezing cycle.
Inertia are similar concepts - inertia is the tendency of an object at rest to
stay at rest, and an object in motion to stay in motion. Inertia can be
summarized as "objects tend to resist changes in motion" whether it be
accelerating or retarding forces. In hockey inertia is evidenced by skaters who
start in a line of travel and then, with no further effort, glide across the ice
for large distances. This is due to the low level of friction (one of the forces
than can impede on inertia's natural inclination to continue in the direction of
travel) of the regelated ice.
Momentum is like inertia in motion. It is a measurement of an objects' mass and
it's velocity, which give an indication of how hard it is to stop the object.
Witness a heavy hockey player who hits a wall or another player. The wall or the
player hit will show the result of dispersing the hockey players' momentum (one
of them may not like it much, either :-). Since momentum is the product of mass
and velocity the same amount of momentum can be generated by a less-heavy hockey
player who travels faster. This is why bullets can damage or kill even though
their mass is small. Their velocity is extremely high and the result is a high
momentum.
I guess that was less brief than I intended (that always happens) - I hope that
was what you were after...
Paul Doherty, CNA, CNE, MCP+I, MCSE, B.A.Sc.
http://members.home.net/iqueue
Rating : 5
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QAId : 1085376
Asker : david_hodges
Subject : weight of water
Private : No
Question : Could you please help settle a bet; How much does an imperial gallon
of water weigh and could you please show your proof.
Answer : My understanding is that a gallon of water weighs 8 pounds at sea
level. Proof? Weigh one yourself and see...
Paul Doherty, CNA, CNE, MCP+I, MCSE, B.A.Sc.
http://members.home.net/iqueue
Rating : 1
End :
Rating : 1
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QAId : 1102946
Asker : sporty21985
Subject : BUMPER CARS
Private : Yes
Question : STATE ONE OF NEWTONS LAWS AND TELL HOW IT APPLIES TO THE BUMPER CARS
Answer : That would be Newton's third law of motion usually summarized as:
For every action there is an equal opposite reaction. This emphasizes that
actions take place among *pairs* of objects. This law applies to bumper cars
since each car imparts it's momentum upon impact to the other car. the angle at
which they strike and the relative velocities of each car dictate what direction
and speed each car will be left with after the collision. Of course bumper cars
have *bumpers* which absorb a great deal of the imparted momentum so the result
is greatly reduced (wouldn't be much fun if they had steel bumpers! :-).
Paul Doherty, CNA, CNE, MCP+I, MCSE, B.A.Sc.
http://members.home.net/iqueue
Rating : 5
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QAId : 1108133
Asker : princegom
Subject : Help! Research!
Private : Yes
Question : Hi! I'm a San Francisco playwright, with a major play opening next
year, funded by a grant from the Gerbode Foundation. I'd like to clarify a
scientific concept as part of my research.
In the play, a character says she's writing a book about an invisible man. She
asks a scientist how, in theory, would one go about becoming invisible. The
scientist explains to her one possibility, in theory. I would like to know how
accurate is the following dialogue:
----------
JULIE
Well, you see, human sight, all sight is only possible with the existence of
light. So reflected or refracted light waves have to bounce off a person in
order for the observer to see them. The light waves have to bounce off and hit
the observer's retina. Now there are some electrons, free electrons, that will
actually absorb all the light coming to it. These electrons will not reflect or
refract light at all. So if you can find a way for this crazy scientist guy in
your book to manipulate these electrons in some way so that they surround his
entire body, I suppose he would be invisible to the human eye. In actuality,
though, he's not invisible; he's just being blocked by these electrons.
GINA
So is there a way to manipulate these free electrons?
JULIE
I can't think of a way.
----------
Thanks, expert, for your help.
Prince Gomolvilas
Playwright-in-Residence
Lorraine Hansberry Theatre
San Francisco
Answer : This is not going ro ring as plausible for one very obvious reason:
If these so-called "free electron" do as described and absorb all the light
striking them, the person will not be invisible, per se, but rather will be
completely black, since no light from the volume of area they take up will reach
an observer's eyes. The observer will see a shape of a person in complete
darkness.
Paul Doherty, CNA, CNE, MCP+I, MCSE, B.A.Sc.
http://members.home.net/iqueue
Rating : 5
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QAId : 1156267
Asker : deskeran@...
Subject : Reflection/Absorption/etc
Private : No
Question : Y'all,
I am unclear on certain aspects of the reflection and absorption of
electromagnetic radiation. I'll briefly tell you what I do know (so you don't
throw the basics at me that I already know) and then ask my question. I know
that atoms absorb photons when that photon's energy matches a transition in that
atom's electron energy levels. This energy is sometimes then emitted as another
photon of the same energy (& color.) So an apple's pigments absorb and then
immediately emit red, right? My question is about what causes transmittance as
opposed to absorption. The apple apparently absorbs most other wavelenghts of
light. Why does it absorb so much, and what happens to this absorbed energy? Why
would this absorbed energy not be emitted as the electron returns to its ground
state? What about a transparent, colored material--what is that doing? What
about wax, which is colorless as a liquid and opaque white as a solid?Also, my
understanding is that a mirror or other reflective surface is working the same
way--a photon is absorbed and then another is released. How, then, is it "aimed"
in the correct direction?
I know this is a lot; answer any or all of it that you care to. Thanks.
Answer : Sorry I took so long to get to this... I took myself off active status
to take a break but it didn't "take" and your question slipped through - I had
to go and take myself off active status again to get it to stick.
As for the question...
The rest of the light that strikes the apple (all but the red frequencies it
re-emits) go into heating the apple. Those frequencies do not "resonate" with
the electron orbits of the apples atoms and thereby only go into molecular
motion.
As far as why some materials are transparent and allow transmission of light
through them a transparent material appears as such because it's natural
resonant frequency for photon absorbtion is higher than the frequencies of
visible light. When an incident photon arrives in a transparent material the
atom's electrons briefly absorb the photon. The electron then "plays" with the
energy from the photon to discover if it's energy matches any of the states at
which the electron can exist. This is called the "virtual state". If the energy
matches, the electron absorbs the energy and may or may not ever re-emit the
photon ("real state"). Most light is re-emitted and passed through the material
after this brief playing, since most frequencies will not match the natural
resonant frequencies within each atom type. This "playing" is why light is
slowed during it's transmission through transparent materials. The higher the
energy of the incident photons, and the closer they match the energy of the
electrons playing with them, the longer the electron plays with the energy
before passing it on. A transparent material would have a color like an orange
does when illuminated with higher-energy photons that match it's quantum states
(so the electrons of the material can permanantly absorb the incident photons -
some to be re-emitted). Since this frequncy is outside our visual range we
simply see the visible light that passes through the material.
Paul Doherty, CNA, CNE, MCP+I, MCSE, B.A.Sc.
http://members.home.net/iqueue
Answer : In that last paragraph I noticed it might be implied that I meant to
say that transparent materials would look like an orange, but in fact I merely
was indicating that, like an orange (or any other normal material that absorbs
most frequencies, while emitting the ones that grant it's appearance),
transparent materials do this at a higher frequency range than for normal
materials.
Answer : Don't forget to rate the answers you receive on AskMe.com.
Answer : Don't forget to rate the answers you receive on AskMe.com
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QAId : 1234347
Asker : Anonymous
Subject : center of gravity
Private : Yes
Question : How would you find the center of gravity of an object when the mass
is not given only the dimension?
Answer : If you can assume the object is of uniform material you can hang the
object by a plumb line (a string) twice from two different points and find where
the paths of the lines through the object intersect. That is the center of mass
for the object no matter it's shape.
Paul Doherty, CNA, CNE, MCP+I, MCSE, B.A.Sc.
http://members.home.net/iqueue
Rating : 5
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QAId : 1241805
Asker : eugenes
Subject : justwannaknow
Private : Yes
Question : 1)can we travel through light?
2)what does radiation mean?
3)for the next few generationms,will be be metamophosized into some sort of
mutant?
4)what happen if we get into black hole?
Answer : 1) Travel "through" light? I don't believe so, although "light"
(radiation) can and does travel through us... X-Rays being a common example.
2) Radiation is a blanket term for any type of electromagnetic phenomena . ER
(Electromagnetic Radiation) covers a broad spectrum of types of radiation, from
infrared, radio waves and microwaves at the low-end to gamma and X-Rays at the
high-end. Sandwiched in the middle of those is what we call "light" and are the
visible wavelengths our eyes are attuned to.
3) Who can say what will happen, but if we were to have some (larger than usual)
mutations I'd think it would take much more than a few generations to take hold.
And that's assuming it's not
A) Fatal
B) Obvious so as to be easily avoided in offspring
4) If you enter a black hole you would be crushed by the gravitional field long
before entering, and be reduced to your constituent parts (atoms) upon entering.
After that, who knows? You might end up under a palm tree in Florida... :-)
Paul Doherty, CNA, CNE, MCP+I, MCSE, B.A.Sc.
http://members.home.net/iqueue
----------------------------------------------------------------------
QAId : 1241806
Asker : eugenes
Subject : justwannaknow
Private : Yes
Question : 1)can we travel through light?
2)what does radiation mean?
3)for the next few generationms,will be be metamophosized into some sort of
mutant?
4)what happen if we get into black hole?
Answer : 1) Travel "through" light? I don't believe so, although "light"
(radiation) can and does travel through us... X-Rays being a common example.
2) Radiation is a blanket term for any type of electromagnetic phenomena . ER
(Electromagnetic Radiation) covers a broad spectrum of types of radiation, from
infrared, radio waves and microwaves at the low-end to gamma and X-Rays at the
high-end. Sandwiched in the middle of those is what we call "light" and are the
visible wavelengths our eyes are attuned to.
3) Who can say what will happen, but if we were to have some (larger than usual)
mutations I'd think it would take much more than a few generations to take hold.
And that's assuming it's not
A) Fatal
B) Obvious so as to be easily avoided in offspring
4) If you enter a black hole you would be crushed by the gravitional field long
before entering, and be reduced to your constituent parts (atoms) upon entering.
After that, who knows? You might end up under a palm tree in Florida... :-)
Paul Doherty, CNA, CNE, MCP+I, MCSE, B.A.Sc.
http://members.home.net/iqueue
----------------------------------------------------------------------
QAId : 1277252
Asker : mrsbrantley
Subject : breaking boards
Private : No
Question : Dear PaulDoherty,
I have a question about "karate" boards. What would be easier to break when
breaking multiple boards: 1) Two 1" boards held together so that there is no
space inbetween.
or
2) Two 1" boards with spacers that separate the boards by say 1/4 to 1/2 inch?
Does the same rule apply as you add more boards say 3 or 4 boards?
This is a really old "arguement"....
Thanks:)
Answer : If this is a really old argument I'd say there are likely to be better
answers than the off-the-cuff one I'm about to give...
My tendency would be to expect an easier time breaking the boards that have the
space between them. Having the boards separated in this way would enable the
first to be broken independent of the later board(s) since they are not
touching. Additionally some of the momentum of hand could be maintained (with
follow-through) and the pieces from the first broken board would be involved in
breaking the next board down.
Paul Doherty, CNA, CNE, MCP+I, MCSE, B.A.
http://members.home.net/iqueue
Answer : Don't forget to rate the asnwers you receive on AskMe.com.
FUQuestion : I think you're right, but what about adding boards to the stack,
say 4 instead of 2? I would imagine this would be the same...isn't there some
physics term for it...something to do with kinetic energy? I don't know I never
got past chemistry...
Thanks
Answer : "Momentum" would be the word I'd apply. You're being allowed to
conserve more of the initial momentum and break "parts" of the whole barrier,
rather than having to sum up enough momentum to break all of them at once.
Paul Doherty, CNA, CNE, MCP+I, MCSE, B.A.
http://members.home.net/iqueue
Rating : 5
Rating : 5
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QAId : 1279825
Asker : V_Ger
Subject : Quantum Computers
Private : No
Question : I recently heard of new device currently being researched at I
beleive MIT. It is a Quantum Computer. The way it supposidly would operate is to
analyze the spin of individual atoms (Their "Quantum State" I think the
technical term is). The question I have to pose is this: Wouldn't the Heisenburg
Uncertainty Principal prevent such a device to be constructed or operate
correctly? Dare I make reference to Schrodinger's cat? :)
Answer : Hehe... I would tend to agree that trying to store or retrieve data
from the *sub*-atomic realms could be difficult, but it sounds like they are
using the atom as a whole, which is less of a bondary due to it's larger size
(well, larger than an individual electron anyway).
Paul Doherty, CNA, CNE, MCP+I, MCSE, B.A.
http://members.home.net/iqueue
Rating : 4
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QAId : 1289774
Asker : cheernbabe02
Subject : Egg drop
Private : No
Question : Hello, for my physics class we need to make a holder for an egg drop
of 15 feet. We can use 5 pieces of computer paper and 1 meter of masking tape.
Do you have any ideas?
Answer : The best thing I can think of would be to conctruct either tails or a
parachute (depending on how thing you can tear the strips) attached to the small
rear of the egg amd use at least one piece of paper as a rolled-up cushion at
the larger end. The tail or shute will help align the egg so it hits on the end
(an egg is strongest in this up-down direction - try squeezing one and see) and
the chute or tails will help decrease the speed of the fall from wind
resistance.
Paul Doherty, CNA, CNE, MCP+I, MCSE, B.A.
http://members.home.net/iqueue
Rating : 5
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QAId : 1304109
Asker : mylittlechicken3
Subject : physics in architecture
Private : No
Question : How are physics used in architecture? If you could just give me an
overview of this it would be very much appreciated. Thanks.
Answer : Architecure (and engineering in general) is like the "art" of physics.
It is a physical manifestation of the principles of physics. So if I had to say
what principle of physics architecture exemplifies I'd have to say it is
Newton's law "for every action there is an equal but opposite reaction". The
whole (functional) idea behind a building is to make a contrivance that will
hold itself up against gravity. The whole design of the infrastructure of the
building is carefully designed to distribute stress and maximize usable space.
We've gotten so good at it and have such strong materials that aesthetics come
into the picture and the buildings can be beautiful as well as functional.
Paul Doherty, CNA, CNE, MCP+I, MCSE, B.A.
http://members.home.net/iqueue
----------------------------------------------------------------------
QAId : 1318642
Asker : robbieg211
Subject : Physics and Surfing
Private : No
Question : I am doing a Science Project on the Physics of Surfing and I was
wondering if you could answer my questiongs.
1) What is the relationship between Vectors and Surfing?
2) Why does a person go faster is riding the wave on the side or at an angle
then when he goes straight in front of the wave?
Thanks For your help. Answer what you can.
Answer : Vectors would be involved (as always in matters of motion) insomuch as
the surfers' final direction of travel is a combination of the vector of
movement imparted to him by the wave and the vector dictated by the angle of
attack of his surfboard.
Now as for you travelling faster when not following the same path as the wave.
When you go in the same direction as the wave the distance travelled and speed
must by definition be the same since it't the wave that is impelling your
movement in the first place. When you travel at an angle to the direction of the
wave you will traverse a greater *distance* than the straight perpendicular line
from wave to shore but you will stay at the forefront of the wave. the result is
that you will travel away from the perpendicular of the wave yet stay even with
it (as you "fall down the front of the wave") so you have travelled a further
distance in the same time. Draw this on a piece of paper with the wave being a
long flat line, and the normal ("straight-ahead") surfer moving in the same
direction. It's easy to see that the surfer covers the same distance as the wave
and so their speeds are the same. Now draw another line representing the surfer
travelling along the wave at a 20-degree angle or so from perpendicular. You
will see that a triangle is formed between where each surfer began (current wave
position), where they each end up after any given period of time, and where the
wave will be at the end of that same time period (both surfers will be laterally
still in line with each other and the wave). It is apparent then that the
"angle-surfer" has travelled a greater distance in the same time so his speed
was faster. As you can then plainly see the triangle formed is a right-triangle
and you can use Pythagoreus's theorem to determine the distance the
"angle-surfer" travelled compared to the wave and straight-ahead surfer. (a^2 +
b^2 = c^2).
Paul Doherty, CNA, CNE, MCP+I, MCSE, B.A.
http://members.home.net/iqueue
Rating : 5
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QAId : 1319814
Asker : nietos
Subject : forces
Private : No
Question : According to my teacher, there are four types of forces in the
universe that control how everything behaves. What are these four forces?
Thanks,
F
Answer : The four forces your teacher is referencing are likely:
gravity
electro-magnetic force
weak nuclear force
strong nuclear force
Paul Doherty, CNA, CNE, MCP+I, MCSE, B.A.
http://members.home.net/iqueue
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QAId : 1331650
Asker : Anonymous
Subject : Center of gravity
Private : Yes
Question : Please... I have no idea how to find the center of gravity of an
object that is like this...
the "*" are just spaces so pretend they aren't there
4 meters wide
___________
|*********|
|*********|2 meters long
|*________|
|*|
|*|2 meters long and 1 meter wide
|*|_______
|_________|1 meter long
Answer : Hanging any object from two or more points by a string will show you
(by drawing a line through the object towards the ground) the object's center of
mass. The point where the two different hanging points lines toward ground
intersect is the center of mass.
For the math-based method (for imaginary objects you don't actually have to
conduct the direct method with above):
http://www.math.wpi.edu/Course_Materials/MA1022A99/center_of_mass/node1.html
Paul Doherty, CNA, CNE, MCP+I, MCSE, B.A.
http://members.home.net/iqueue
FUQuestion : So how would I answer the question?
Answer : Is this homework? I don't answer people's homework for them (and in
this case I don't know the formula - weren't you given the formula with the
assignment?).
Paul Doherty, CNA, CNE, MCP+I, MCSE, B.A.
http://members.home.net/iqueue
Answer : If you *were* given the formula I'd be interested to know what it is...
and could assist you in working it out.
Paul Doherty, CNA, CNE, MCP+I, MCSE, B.A.
http://members.home.net/iqueue
FUQuestion : there is no equation given and its not a homework problem. I'm not
even in school. It was just a question I can figure out
Answer : Oh ok...
Well in this case it appears that without having the actual object in-hand (in
which case you could conduct the experiment I suggested in my first response)
you would have to employ some ugly calculus. The details of which are in that
URL I put in the first response.
Paul Doherty, CNA, CNE, MCP+I, MCSE, B.A.
http://members.home.net/iqueue
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QAId : 1341229
Asker : Anonymous
Subject : Waves
Private : No
Question : Hi Hi! I'm very interest in this science, so i want to learn more
about the physics. I hear my friend which studying Physics told me that they are
learning waves. B/c i don't have time to take Physics this year. So i have no
idea where i can find the answer to my question. I know the meaning of speed and
amplitude, but i want to know that is amplitude depend on speed?
Answer : You're a bit confused - let's see if I can help. Speed of a wave is a
function of two simple items - frequency and wavelength. Frequency is how many
times a wave oscillates per second, and wavelength is the distance between
identical portions of the waveform. If you multiply the frequency times the
wavelength (distance travelled per oscillation) you will get the speed of the
wave's travel.
Amplitude is an unrelated term that refers to how far above or below a "zero"
value a wave is at any particular moment. The easist analogy is sound. A loud
sound has a higher wave crest than a softer sound - we would then say the
amplitude of a loud sound is higher than for the softer sound.
Paul Doherty, CNA, CNE, MCP+I, MCSE, B.A.
http://members.home.net/iqueue
Rating : 4.8
Rating : 4.8
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QAId : 1678904
Asker : Echang14
Subject : Effects of Gravity
Private : No
Question : I have a project to construct a device that will protect an egg that
is dropped off of a two story building. I am suppose to use my knowledge of
physics to counter the effects of gravity upon my egg.
These are the materials allowed:
Up to 150 soda straws, tape, string, propellers, rubber bands, glue, wire, wood
and cylafang.
The teacher said that we couldn't wrap 50inches of tape around it to prevent the
egg from breaking. He also said that the egg must be visible (not totally
covered and protected). Also, no parachutges or balloons or cords are allowed.
The device must impact the ground also.
I need an idea to maybe get started.
I figured out that i could probably slow it down using propeller with rubber
bands, but this doesn't save my egg from cracking or breaking.
What suggestions do you have?
Thank you.
Answer : I would probably build a cage out of the soda straws and suspend the
egg inside it (towards the top) with the rubber bands.
Or use the 150 soda straws arranged in a circular fashion around the heavy end
of the egg (when viewed from the side picture the egg upright with a large 'X'
of soda straws supporting it) - if you can fashion a grouge chute (anything
attached to the back to create drag) you can slow the descent slightly and force
the egg to stay facing down as it falls.
Good luck!
Paul Doherty
http://members.home.net/iqueue
FUQuestion : how do i suspend the egg in the middle?
Answer : With the rubberbands was how I was picturing it - the actual logistics
will have to be worked out by you, I was just trying to forulate a plan.
Paul Doherty
http://members.home.net/iqueue
Rating : 3
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QAId : 1702816
Asker : JackofAllTrades
Subject : Ski length and ski wax vs speed
Private : No
Question : This is a two part question.
First, Why do you go down hill faster on longer skis? Is it because you can ride
out the tiny bumps better; or because more of the snow will become water under
the ski, thus less friction; or something else altogether?
Second, Why does ski wax make you go faster? If you run your hands through
freshly waxed skis, it seems to have more friction.
This is part of ongoing arguments I have been having with my friends for awhile.
TIA,
Answer : My quick answer would be to say that the process of snow skiing is very
similar to that of ice skating, in that you are indeed travelling over a thin
surface of melted ice (or snow). This process is called 'regelation'. In the
case of a longer ski (assuming width is a constant between the ski types) you
may melt less ice/snow with the longer ski due to the increased surface area
(and corresponding lower pressure per unit of surface area). Here is a
conversation by some skiers that is fun but doesn't shed much light on the
subject - click "next in thread" to read on...
http://x55.deja.com/getdoc.xp?AN=587333646&search=thread&CONTEXT=962549340.1485963300&HIT_CONTEXT=962549303.1484259547&HIT_NUM=&hitnum=2
Paul Doherty, CNA, CNE, MCP+I, MCSE, B.A.
http://members.home.net/iqueue
Rating : 5
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QAId : 1754356
Asker : Anonymous
Subject : How do sound (and radio) waves travel?
Private : No
Question : I understand that a wave must have a medium to travel through (it
can't travel through a vacumm)as it's the vibration of molecule that carry the
wave. I assume that each molecule knocks in to the next one, passing on energy,
which causes that to vibrate and so on. I also assume that on each 'knock'
energy is lost, until the energy is so small that the wave can not be detected.
Sound waves travel in the audiable spectrum, radio is a sound wave that is added
to a carrier wave which is outside of the audibility and then the radio receiver
converts this back to audible sounds when it receives it. Each radio station
uses a different frequency carrier wave.
(1)How do all these different frequencies (sound, radio, TV, mobile phone)
travel? (2)How do molecules vibrate at all of these frequecies at the same time?
(3)Are we constantly surrounded by molecules vibrating as a result of radio / TV
/ Mobile phone? (4)Do any of the molecules in our bodies vibrate due to these
waves?
Hope there aren't too many question there for you.
Answer : The main thing you are missing here is that of the phenomena you are
discussing only one is a physical wave - sound. Radio waves, microwaves (mobile
phones), and television are all signals carried on *electromagnetic waves*.
Electromagnetic radiation is a form of pure energy and requires no medium for
transmission (infact mediums just get in the way - that's why light from the sun
is slowed slightly and bent by the air in our atmosphere or by water when
looking into a pool or bathtub).
As far as the molecules of your body oscillating in rhythm to some of these
frequencies of radiation I'd have to say that yes some do. And some frequencies
are more powerful than others - some of which can cause cell damage and our not
so nice friend, cancer.
I hope that answered your question(s)...
Paul Doherty, CNA, CNE, MCP+I, MCSE, B.A.
http://members.home.net/iqueue
Rating : 4
FUQuestion : So are radio waves etc classed as 'light' waves?
How does this energy travel from one place to another?
Answer : Yes, radio waves are the same phenomenon as visible light - just of a
longer wavelength. It is pure energy (as opposed to a mechanical vibration such
as sound waves, which are truly defined by their medium) which is why is needs
no transmission medium. Sunlight is a perfect example - it is a mishmash of ER
frequencies and travels a vast distance to arrive at Earth in the same form it
was when is was emitted.
Paul Doherty, CNA, CNE, MCP+I, MCSE, B.A.
http://members.home.net/iqueue
FUQuestion : Paul,
You refer to Radio (and light) waves as pure energy, but what is pure energy?
and where does this energy come from?
Regards,
Richard.
Answer : The energy can come from heat, motion, electrical or magnetic forces,
or from other sources of ER.
When an atom becomes excited, by physical or electrical means, it's electrons
become elevated to levels above their normal orbits. These electrons then drop
back to their normal unexcited state and in the process give off the energy they
gained. Since the orbits are at definite levels apart from each other, and since
the electrons cannot reside between these levels, the energy given off by an
electron going through this de-excitation process is said to be quantized.
Quantization in this usage means that the energy is given off in discrete steps
of energy. This excitation and atomic quantization is where we get some of the
things familiar to us. As you probably already know electromagnetic radiation
(I'll call it ER from here on out) in the ranges that our eyes use is generally
called "light". So light is produced by this same mechanism - electrons get
excited up to a higher-than-normal orbit, and then de-excite, giving off the
energy they had gained in the form of a photon (quantized "piece" of ER).
Here's a good example of the quantization of light. I'm sure you've seen the
so-called neon signs in convenience stores and such? Those signs are an
excellent example of the quantized nature of electron orbits. Those lamps
contain a pure gas - in the case of the bright red ones it's neon. The
particular combination of electron excitation/de-excitation steps available to
the neon atoms is what gives neon it's characteristic red color. Argon is
another gas used in these lights and has a blue color for the same reason. Each
type of gas has it's own characteristic pattern of available electron orbit hops
that give it unique color. Contrast these types of lights with an incandescent
light like in your house or on your car. These use a metal filament which when
heated glows and gives off light. the same process if happening as in the gas
but we get (closer to) pure white light from this type of bulb. Why? It's
because now, instead of the limited nmber of combinations of electron orbit hops
we had with a gas (where atoms are relatively far apart), we have a solid
material with atoms shoved close together. The result being that electrons who
make a hop to higher energy orbit in one atom may very well de-excite into a
nearby atom making the energy patterns closer to infinite which also makes the
frequencies of emitted ER nearly infinite - white light. A flourescent bulb
works like a neon light but produces white light. How is that? It uses mercury
vapor inside the tube, which when a current is passed through excites and gives
off the standard limited number of patterns a gas can produce. But this light
isn't even visible - it's ultraviolet in frequency. the white light actually
comes from the spray coating on the inside of the tube - this solid material
absorbs, and becomes excited by, the UV light and in turn gives off it's own
less-limited pattern of white-ish light.
Paul Doherty, CNA, CNE, MCP+I, MCSE, B.A.Sc.
http://members.home.net/iqueue
FUQuestion : Paul,
Thanks for all your answers. They are very interesting. Hope you don't mind me
answering so many follow up questions. Please let me know if you do.
I think that I understand how light works now, however could you tell me if I'm
on the right track.
I have number my questions and assumptions so that it is easier for you to
reply.
Atoms in a light bulb are excited by electricity which causes their electrons to
move into a higher orbit. When they fall back to their original orbit they give
out energy [photon]. (1)I assume that in the sun this is caused by a chemical
reaction(?). We see objects because light [photons] bounces off them and are
then enter our eye which the brain interpretates.(2) Do the photons actually
'bounce' or does the photon that hits the object cause a new photon to be
omitted? (3) I assume that we see colour because a red object only reflects red
light, a yellow object only yellow light etc.
(4) So if I have the above right, then an objects colour depends on the
different atoms within an object. Each different atom emits a different amount
of red or blue or green which 'combine' to produce the final colour.
(5) If a near infinite number of photons are travelling in all direction all of
the time, then do these photon colide and if so what happens?
The different colours (different frequencies of photons) that we see are due to
different atoms having different distances that their electrons travel between
the normal and excited state. Going back to one of my first topics, (6) how are
radio waves created? I appreciate that these 'waves' are just photons with a
different frequency (energy level) but how does a transmitter create them?
Thanks again for your answers.
Regards,
Richard.
Answer : 1. In the sun light is generated as mass is *directly* converted to
energy from mass. The sun is a huge nuclear fusion reactor, turning hydrogen
atoms into helium and other light elements. The disparity between the
mass-per-nucleon (namely the huge reduction in MPN going from hydrogen to
helium) is where this ER and heat come from.
2. Photons are "re-emitted" - the mass that makes up any object can be thought
of as being "in tune with" certain frequencies of light, much like a tuning
fork. If you shine white light on the object all frequencies are absorbed as
heat except the ones to which the material is "resonant". The resonant ones
energy goes into the elevating into higher orbits and re-emission of another
photon.
3. Yes... Answered in #2 above.
4. The object re-emits those frequencies to which it is attuned.
5. Light travels and interacts both as a wave (like gravity or magnetism) *and*
as a particle. This is one of the great apparent paradoxes of light. So I would
say that interference patterns would be the result, with constructive and
destructive interference the result. But I can not definitively state this
without research and I haven't the time to do so tonight.
6. As for how a radio transmitter works here is a good description of the rapid
oscillating electric charges that run up and down the antenna:
"Electromagnetic waves are created whenever electrically charged particles
change speed or direction; whenever they accelerate. Since there are
accelerating electric charges everywhere--thermal energy keeps them moving
about--there are also electromagnetic waves everywhere. But the radio waves used
in communications systems are generated deliberately by moving electric charges
back and forth. When charges are sent up and down a radio antenna, these charges
are accelerating and they form complicated electric and magnetic fields that
include electromagnetic waves. Once launched, those electromagnetic waves
propagate through space at approximately the speed of light."
A radio station launches a radio wave by moving electric charges rhythmically up
and down their antenna. As this electric charge accelerates back and forth, it
produces a changing electric field--a structure in space that pushes on electric
charges--and a changing magnetic field--a structure in space that pushes on
magnetic poles. Because the electric field changes with time, it creates the
magnetic field and because the magnetic field changes with time, it creates the
electric field. The two travel off across space as a pair, endlessly recreating
one another in an electromagnetic wave that will continue to the ends of the
universe. However, when this wave encounters the antenna of your radio, its
electric field begins to push electric charges up and down on that antenna. Your
radio senses this motion of electric charges and thus detects the passing radio
wave.
And continuing...
"To convey audio information (sound) to you radio, the radio station makes one
of several changes to the radio wave it transmits. In the AM or Amplitude
Modulation technique, it adjusts the amount of charge it moves up and down its
antenna, and hence the strength of its radio wave, in order to signal which way
to move the speaker of your radio. These movements of the speaker are what cause
your radio to emit sound. In the FM or Frequency Modulation technique, the radio
station adjusts the precise frequency at which it moves charge up and down its
antenna. Your radio senses these slight changes in frequency and moves its
speaker accordingly."
The last gleaned from the website:
http://rabi.phys.virginia.edu/HTW//
--
Paul Doherty, CNA, CNE, MCP+I, MCSE, A.A., B.A.
http://members.home.net/iqueue
Home of PC DiskMaster and other Windows utilities
----------------------------------------------------------------------
QAId : 1754417
Asker : Anonymous
Subject : How do sound (and radio) waves travel?
Private : No
Question : I understand that a wave must have a medium to travel through (it
can't travel through a vacumm)as it's the vibration of molecule that carry the
wave. I assume that each molecule knocks in to the next one, passing on energy,
which causes that to vibrate and so on. I also assume that on each 'knock'
energy is lost, until the energy is so small that the wave can not be detected.
Sound waves travel in the audiable spectrum, radio is a sound wave that is added
to a carrier wave which is outside of the audibility and then the radio receiver
converts this back to audible sounds when it receives it. Each radio station
uses a different frequency carrier wave.
(1)How do all these different frequencies (sound, radio, TV, mobile phone)
travel? (2)How do molecules vibrate at all of these frequecies at the same time?
(3)Are we constantly surrounded by molecules vibrating as a result of radio / TV
/ Mobile phone? (4)Do any of the molecules in our bodies vibrate due to these
waves?
Hope there aren't too many question there for you.
Answer : The main thing you are missing here is that of the phenomena you are
discussing only one is a physical wave - sound. Radio waves, microwaves (mobile
phones), and television are all signals carried on *electromagnetic waves*.
Electromagnetic radiation is a form of pure energy and requires no medium for
transmission (infact mediums just get in the way - that's why light from the sun
is slowed slightly and bent by the air in our atmosphere or by water when
looking into a pool or bathtub).
As far as the molecules of your body oscillating in rhythm to some of these
frequencies of radiation I'd have to say that yes some do. And some frequencies
are more powerful than others - some of which can cause cell damage and our not
so nice friend, cancer.
I hope that answered your question(s)...
Paul Doherty, CNA, CNE, MCP+I, MCSE, B.A.
http://members.home.net/iqueue
Answer : Don't forget to rate the answers you receive on AskMe.com
Answer : Ignore that reminder to rate the answer - I didn't remember that this
question was accidentally aske