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Category : PhysicsPowerUsers.info - Paul Doherty Askme Archive of Questions and Answers
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QAId : 2727024
Asker : priyaimports@...
Subject : little doubt
Private : No
Question : thank u sir but i have doubt.you said that momentum is what makes
things harder to stop .is it a force.for eg: we can take two cars A and B go in
same direction IN THIS WERE IS THE MOMENTUM.WHEN A COLLIDES WITH B IS IT THE
MOMENTUM.TO PROVE IS THERE ANY EXPERIMENT
Answer : If A and B are travelling in the same direction how ill they collide?
:-)
Their momentum is expressed as the effort it will take to bring them to rest. So
a car travelling alone (without hitting anything) has momentum by virtue of the
fact it will take X amount of force expenditure to bring it to a halt. Another
word for this resistance to stopping is called impetus.
--
Paul Doherty, CNA, CNE, MCP+I, MCSE, A.A.Sc., B.A.
http://members.home.net/iqueue
Home of PC DiskMaster and other Windows utilities
Rating : 5
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QAId : 2730874
Asker : jhala1313
Subject : help
Private : No
Question : hi,
An amusement park ride features a small electric replica of the ThrustSSC car
running on a straight, 600 foot, track. The car always moves with constant
acceleration, positive or negative.
You have two controls: A and D. A causes the car to accelerate with constant
acceleration, D causes the car to decelerate with constant deceleration. The
magnitude of the acceleration is twice the magnitude of the deceleration. There
are markings on the side of the track in 1 ft intervals.
To start the car you press control A. How far along the track should you travel
before pressing control D so that car will stop exactly at the end of the track?
Roger
Answer : I'm going to say you'll need to apply the D (eceleration) button at the
200 foot mark so it will be applied for twice as long a distance as the
acceleration button was depressed (since it decelerates at half the rate the A
button accelerates at).
--
Paul Doherty, CNA, CNE, MCP+I, MCSE, A.A.Sc., B.A.
http://members.home.net/iqueue
Home of PC DiskMaster and other Windows utilities
Rating : 4
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QAId : 2736909
Asker : raptor660123
Subject : torque
Private : Yes
Question : Yeah I want to know how to measure ft.lb of torque, For example I
know that a one foot pole with one pound of down force on the other end will be
1 ft.lb of torque at this end (longer pole more torque). But I want to know what
1 ft.lb of torque is equivalent to in normal pounds ?
Answer : Open this URL:
http://www.unc.edu/~rowlett/units/dictP.html
Press CTRL-F and type torque - it has definitions for all types of units.
--
Paul Doherty, CNA, CNE, MCP+I, MCSE, A.A.Sc., B.A.
http://members.home.net/iqueue
Home of PC DiskMaster and other Windows utilities
End :
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QAId : 2762921
Asker : ruko
Subject : Jet boat propulsion/airplane wings
Private : No
Question : Dear Sir
Two questions sir:
1) For the benifit of a friend of mine please explain why jet boat exhaust is
above the water surface rather than below it.
2) An airplane wing has a certain shape that allows air to flow faster over the
top than on the bottom of it. This creats a lower pressure on top which allows
the pressure under the wing to create lift. It is called the Bernoli affect
(pardon the spelling). This is what is taught in most text books. If this is the
only reason why airplanes can fly, how do airplanes fly upside down?
Thank you.
Ruko
Answer : #1 I would expect it's because jets (ala jet airplanes) operate on a
principle of instake of air and exhaust of same at higher velocities. IOW - it's
not a "water" jet, it's an air jet engine being strapped onto a boat.
#2 - The majority of lift is *not* generated by the Bernoulli effect - it is
generated by the forward speed of the plane and the angle of the wing. The
faster the plane travels the more air molecules strike the underside of the wing
since it is angled upwards. As to why a plane can fly upside down - the
Bernoulli effect and the main lift generated by the air striking the underside
of the wing are not based on orientation - they are based on forward speed. So
it doesn't matter whether the plane is upside down or sideways - the lift is
still generated. All other directions of travel (as in to not have "lift"
towards the ground which is what you were implying I think) are still a function
of the control surfaces of the plane (tail rudder, ailerons, flaps).
--
Paul Doherty, CNA, CNE, MCP+I, MCSE, A.A.Sc., B.A.
http://members.home.net/iqueue
Home of PC DiskMaster and other Windows utilities
FUQuestion : Dear Sir
Jet boat propulsion:
I am referring to the "personal water crafts" like Yamaha, Skidoo etc. The ones
that are driving people nuts on lakes and rivers. They have a pump which forces
a "jet" of water out the back driving the boat forward. The exhaust or jet is
above the water and I was wondering why it would not be below the water surface.
Thanks
Ruko
Answer : Oh... well for those I'd expect it's because the engine burns gasoline
and air (oxygen). And because if the exhaust *were* placed underwater (to
somehow get some extra "boost" if that's what he means by this question) there
is a threat (when not under full throttle) of getting water back up *into* the
engine which is a Bad Thing (tm).
--
Paul Doherty, CNA, CNE, MCP+I, MCSE, A.A.Sc., B.A.
http://members.home.net/iqueue
Home of PC DiskMaster and other Windows utilities
FUQuestion : Paul
Thank you for your response.
The "exhaust" I'm talking about is not engine exhaust. I am sorry I used the
word exhaust, it probably does not fit here. I am talking about the jet of water
out of the nozzel in back that drives the little annoying boats forward. It is
above the water surface. My question is why is it above the surface rather than
below it?
Thanks
Ruko
Answer : Are you referring to this stream that is ejected from the back-top of
the waverunner?:
http://www.yamaha-motor.com/01watercraft/01wcimages/500/01XL12_ACTION_L_500.jpg
If so, I'd suggest it is simply a pressure-relieving mechanism and the primary
output of the "jet" is indeed submersed. It probably helps avoid undue pressure
build-up in the engine/jet area due to water pressure fluctutations.
--
Paul Doherty, CNA, CNE, MCP+I, MCSE, A.A.Sc., B.A.
http://members.home.net/iqueue
Home of PC DiskMaster and other Windows utilities
Answer : Don't forget to rate the answers you receive on AskMe.com...
Rating : 4
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QAId : 2783937
Asker : ronaldsharko@...
Subject : physics, volume of a brick
Private : No
Question : freshman physics. How do I find the weight and volume of 1/2 brick?
Answer : I assume you can get the weight easily with a scale.
The volume is easy to obtain too... Simply fill a jug, or other device large
enough to hold the entire brick, with water to the very top, placing this whole
device inside another (like a ice tea pitcher filled with water sitting inside a
tupperware rectangular bin). Now simply (slowly) introduce the brick into the
water-filled pitcher (being sure not to put your fingers or hands into the water
too). The water that gets displaced is equal to the volume of the object that
displaced it. So all you have to now is pour the water that was displaced (and
captured) into the tupperware and pour it into a measuring cup marked with
measurements and you will have the volume of an irregular object such as this
brick.
--
Paul Doherty, CNA, CNE, MCP+I, MCSE, A.A.Sc., B.A.
http://members.home.net/iqueue
Home of PC DiskMaster and other Windows utilities
Rating : 5
Answer : You can find the mass by using a balance (scale with two sides, a pan
on each side, suspended by a frame). This differs from a normal "weighing"
scale, in that it does not measure the force of gravity on the object (it's
"weight"), but rather to bring the balance into equilibrium, an *equivalent
mass* must be placed on the opposite side balance pan. This means that you can
use the little metric weights (masses) with handles on them that come in 1gm,
1mg, etc sizes to balance the brick and find it's mass. This works where a scale
does not because it is independent of any other factors. You can successfully
find the mass of the brick as easily on Earth as on the surface of the moon,
even though the moon's gravitational pull (nad the resultant wight produced) are
only 1/6 that of Earth.
--
Paul Doherty, CNA, CNE, MCP+I, MCSE, A.A.Sc., B.A.
http://members.home.net/iqueue
Home of PC DiskMaster and other Windows utilities
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QAId : 2785576
Asker : rfeinberg61
Subject : what is a coulomb
Private : No
Question : I am taking a basic electronics course. The definition given of a
coulomb is the charge possessed by 6.25 x 10 (to the power of 18) electrons.
Where did that number come from? If it was an arbitrary number set as as
standard, why that number.
Answer : For electrically-charged objects this amount just happened to turn out
to be a constant of attraction/repulsion (since the charges can be considered to
be unchanging, the only other changing factor between comparing
repulsion/attraction was distance).
--
Paul Doherty, CNA, CNE, MCP+I, MCSE, A.A.Sc., B.A.
http://members.home.net/iqueue
Home of PC DiskMaster and other Windows utilities
FUQuestion : I now understand that the number 6.25x10^18 is a constant. But
could you clarify what is meant by a constant of attraction/repulsion?
Answer : The electrical repulsion/attraction force, when measured, was found to
fit the following formula:
F = k * (q1 * q2)/d^2
F is the force of attraction/repulsion
k is the constant (later defined as a coulomb)
q1 and q2 are the charges themselves
d is the distance between the charged particles (being squared here)
The formula was made to fit our experience of the world as we found it, not the
other way around. Charles Coulomb happened to find that when the other elements
of the equation are put in with this contant value the force could be predicted.
So the value got a name (coulomb) and we got a formula that fits our reality and
allows us to make some more predictions. That's how these things work - not
always a tidy explanation, but an item that is useful in describing and working
with the things we know/explore.
--
Paul Doherty, CNA, CNE, MCP+I, MCSE, A.A.Sc., B.A.
http://members.home.net/iqueue
Home of PC DiskMaster and other Windows utilities
Rating : 5
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QAId : 2788099
Asker : bijuo
Subject : blackholes
Private : No
Question : what is a black hole and do you know anything about time-space
continum?
Answer : A black hole is a collapsed star I believe... it has surpassed the mass
required for it to generate a gravitational field so strong that light can no
longer escape from it's immediate vicinity (which is why it appears as an empty
space).
Time-space continuum? I think that is an acknowledgement that you can't discuss
time without involving the concept of space, since all of our concepts of time
involve motion (Earth around the sun, etc).
--
Paul Doherty, CNA, CNE, MCP+I, MCSE, A.A.Sc., B.A.
http://members.home.net/iqueue
Home of PC DiskMaster and other Windows utilities
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QAId : 2812411
Asker : elisehague
Subject : efficiency of a golf ball
Private : Yes
Question : How does the surface effect the way a golf ball bounces?(does it have
anything to do with friction?)
Also, how does the temperature of a golf ball effect the way it bounces?
Thanks
Answer : I don't think that a golf ball's bounce or roll is significantly
affected by the "dimpling" on the ball surface. Spin of the ball when it lands
and velocity (includes direction as well as speed of travel) are the primary
factors. The dimpling does help to generate lift while the ball is in flight.
Depending on the spin imparted to the ball the ball can climb, drop faster, or
veer left or right (as anyone who has shot them into the woods can testify :-).
I would say that the warmer the ball the higher it will bounce. Since the core
is rubber and rubber becomes less flexible the colder it gets (and more the
earmer it gets) it stands to reason it will bounce higher when warm. Try putting
a rubber "superball" into a freezer for a few hours and examine it's lost
elasticity when bounced for an extreme example.
--
Paul Doherty, CNA, CNE, MCP+I, MCSE, A.A.Sc., B.A.
http://members.home.net/iqueue
Home of PC DiskMaster and other Windows utilities
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QAId : 2839487
Asker : ronaldsharko@...
Subject : PHYSICS
Private : No
Question : THANKS FOR YOUR HELP. HOW DO I CONVERT 500 MILLALITERS TO
CENTIMETERS.
Answer : 500 millimeters ("milli" meaning 1000 - 1000mm = 1 meter)
is equivalent to 1/2 of a meter's worth of centimeters. Since there are 100
centimeters in a meter ("cent") then this would be:
50 centimeters
So 500mm = 50cm
--
Paul Doherty, CNA, CNE, MCP+I, MCSE, A.A.Sc., B.A.
http://mem`bers.home.net/iqueue
Home of PC DiskMaster and other Windows utilities
Rating : 5
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QAId : 2863211
Asker : michaelg21386
Subject : The Dangers of Electricity
Private : No
Question : Why is electricity dangerous to humans? Is high voltage and low
current or high current and low voltage more dangerous and why?
Hope you can help, Michael
Answer : Electricity can interfere with the nervous system. Plus it causes
severe muscle contractions, and if there is enough current can cause severe
burns.
Both voltage and current are dangerous.
Voltage is what gets the electricity into you; current is what kills you.
--
Paul Doherty, CNA, CNE, MCP+I, MCSE, A.A.Sc., B.A.
http://members.home.net/iqueue
Home of PC DiskMaster and other Windows utilities
Rating : 3
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QAId : 2953953
Asker : WWJONES35
Subject : Video & Audio Tapes about Physics
Private : No
Question : I enjoy the video & audio tapes written by Stephen Hawkins " A Brief
History of Time & Universe." They are presented in a clear, understandable,
concise manner- not redundant, superfluous or self-serving.
Conversely, I recieved as a gift, some audio tapes entitled "The Great Courses
on Tape, Einstein's Relativity and the Quantun Revolution: Modern Physics for
Non-Scientist Part I and Part II," put out by "The Teaching Company" of
Springfield, VA, which I rate as D+!!!
Do you know of a source for Video and Audio Tapes of General Science and/or
Physics?
Answer : I found many by going to amazon.com and performing a search (in Books)
for
audio physics
--
Paul Doherty, CNA, CNE, MCP+I, MCSE, A.A.Sc., B.A.
http://members.home.net/iqueue
Home of PC DiskMaster and other Windows utilities
Rating : 2
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QAId : 2971084
Asker : Anonymous
Subject : speed of light
Private : No
Question : What is 4.7 times faster than the speed of light?
Answer : A serious speeding ticket that will lose you your license...
No seriously... this sounds like a trick question but I'll answer it anyway.
4.7 x 186,282 = 875,525.4 miles per second.
This number 4.7 seems familiar... are you leading up to some kind of speed
insinuation for an original IBM PC (X86 running at 4.77 Mhz)? hehe
--
Paul Doherty, CNA, CNE, MCP+I, MCSE, A.A.Sc., B.A.
http://members.home.net/iqueue
Home of PC DiskMaster and other Windows utilities
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QAId : 2973210
Asker : lilstinkis
Subject : ELECTROMAGNETIC PESTICIDES
Private : Yes
Question : HELLO~
I'M GLAD THAT I SAW YOUR NAME. YOU SEEM TO KNOW MUCH ABOUT THE ELECTROMAGNET
SUBJECT. PLEASE HELP ME FIND THIS ANSWER. MY FIANCE AND I ARE MOVING TO MD IN
ABOUT 2 1/2 WEEKS AND I MUST STAY WITH MY SISTER IN LAW FOR 4 WKS WHILE OUR
HOUSE IS BEING CONSTRUCTED. SHE USES THAT PESTICIDE CALLED RIDDEX PLUG IN
ELECTRONIC UNIT. I CANNOT SEEM TO BE ABLE TO TALK HER INTO UNPLUGGING THE UNIT
WHILE WE STAY WITH HER. I OWN 2 FERRETS, A GUINNEA PIG, AND A CAT. I HAVE ALSO
HAD 2 BRAIN SURGERIES AND 8 CEREBRAL HEMORRAGES. I AM SO CONCERNED ABOUT THE
ELECTROMAGNETIC PULSES BOTH HARMING MY ANIMALS AND MYSELF. PLEASE HELP!!! (BY
THE WAY QVC SEEMS TO BE THE ONLY PLACE THAT EVEN CARRIES THIS UNIT. ONE IS
NEEDED ON EACH FLOOR TO REMAIN AFFECTIVE. WE WILL BE STAYING IN A 90% CONCRETE
UNFINISHED BASEMENT)
Answer : I am not familiar with this unit but just upon inspection of the QVC
non-technical description it appears that at the very least your guinea pig and
perhaps the ferrets will not be able to tolerate the fields given off by these
devices.
http://www.qvc.com/asp/frameset.asp?nest=%2Fasp%2FIsItemNumberRedirect.asp&search=SQ&frames=y&referrer=QVC&txtDesc=riddex
I would suggest that you ask her nicely once again and if she will not (amazing
considering your history of problems - if I even suspected it *might* have an
effect on you I would remove it without question!) then I'd suggest you make
other plans for a place to stay for those 4 weeks. Ask her how she might feel
were you to have a stroke due to her refusal? A treatment of a traditional
insecticide could easily take the place of these devices for the month you'll be
there.
--
Paul Doherty, CNA, CNE, MCP+I, MCSE, A.A.Sc., B.A.
http://members.home.net/iqueue
Home of PC DiskMaster and other Windows utilities
Rating : 5
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QAId : 2993306
Asker : priyaimports@...
Subject : momentum
Private : No
Question : dear sir
in same topc i have a doubt .let us consider
two bodies coming with same velocity with same
mass .if you stop the body before it collidesit momentum will be high due to
high velocity.but after it collides it momentum will be less because it velocity
will reduce .then who can they say .momentum after impact = before impact
Answer : You can say there was momentum before impact because you now see the
results of the needed forces to bring those objects to a halt - namely, both are
now *not* moving and if objects such as cars were involved you see the force
required to bring them to rest in the form of smashed cars. I'm really not sure
where you're confused.
--
Paul Doherty, CNA, CNE, MCP+I, MCSE, A.A.Sc., B.A.
http://members.home.net/iqueue
Home of PC DiskMaster and other Windows utilities
FUQuestion : THAK YOU SIR I UNDERSTOOD IT. NOW WE CAN TAKE THE TOPIC .CURRENT ,
IN TELEVISION WHAT WHO CURRENT ENERGY IS CONVERTED TO VISION. IS CONVERTED IN TO
WHAT.WHAT IS PRESSURE.
THEY SAY ATOMIS A SMALLEST PARTICAL.PROTONS
,ELECTRONS AND NEWTRONS ARE REVOLVING ARROUND THE ATOM WHO DO THEY SAY WITH WHAT
REASONS WHAT IS CURRENT AND WHAT INSIDE IT OF WHAT T IS MADE I WHAT TO DETAILE
STUDY ABOUT CURRENT
Answer : That question is hard to read, but I think I got parts of it.
A TV works by shooting a scanning beam of electrons to the inside surface of the
TV tube (which is coated inside with phosphors). The phosphors on the inside of
the TV are excited and emit light of an intensity based on the excitation levels
given it. The different colors come from combining each "element" on the screen
into what are called "triads". These triads consist of a red, green and blue
element, all three together making one visible item on the screen.
As for atoms being the smallest units I believe the "quarks" have that
distinction at the moment. They are building blocks of the atomic parts
(electrons, protons, and neutrons). As for the orbits the electrons "orbit"
(actually "exist at a particular place inside an orbit shell whenever they
please" is a more accurate statement) a nucleus that is composed of protons and
neutrons.
Current is simply the flow of electricity measured in units of time.
--
Paul Doherty, CNA, CNE, MCP+I, MCSE, A.A.Sc., B.A.
http://members.home.net/iqueue
Home of PC DiskMaster and other Windows utilities
Answer : Don't forget to rate the answers you receive on AskMe.com...
FUQuestion : in every particals ther is atom in the atom theris nucleuse and in
the nucleuse ther are protons and neutrons .they are positive and nagative
charge.what do you mean positiveand negative charge.what is a charge.beam of
electrons.who do they say that the protons and electrons revolve around the
neucleus .what to no reason behind every thing
Answer : Protons are positive in charge. Neutrons have no charge. Electrons are
negative in charge and "orbit" the nucleus.
--
Paul Doherty
http://members.home.net/iqueue
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QAId : 3040633
Asker : demund_98
Subject : cycling
Private : No
Question : I would like to know all physics involved wehn i am cycling an
exercise bike such as energy transformation, torque (crank/pedal etc) involved
when I pedal, inertia of the wheel, how did the bike get my RPM etc. I would
hope that you can be as detail as possible and covers anything that has got to
do with physics. Thank You
Answer : Torque is calculated rather simply - assuming you attack the pedal at a
perpendicular (most of the time that is true) the torque you produce is simply
the force you apply times the distance from the pedal to the fulcrum (in this
case the point where the pedal terminates into the crank) minus and retarding
forces. As for energy trasnformation there is of course chemical to mechanical
energy transformation in you as you convert that cheeseburger into muscle
movement. ;-) Inertia of the wheel would apply mainly on the initial startup of
the wheel. Once it's moving it is easier to keep moving (rolling friction it's
called). Rotational inertia of the wheel then steps in, but it has more to do
with keeping the wheel pointed straight ahead (resisting sideways torques). This
is part of what keeps bicycles easily controllable at speed (and keeps you from
falling over). The bike gets the RPM probably from having a sensor on the frame
that can tell when a part of the tire/wheel passes by it. Then it simply counts
how often that part passes by over a given period of time and that gives the
RPM. So say you are pedalling hard and the sensor sees the "flag" pass by 10
times in 10 seconds. Then the RPM would be calculated (for that instant) as 60
RPM since if that rate were maintained you would do 60 flag passes in 60
seconds.
More info on the physics of cycling can be had in these two other answers I've
previously given...
http://www1.askme.com/SearchResults.asp?pm=va&cid=852&xShowNew=1&QA=on&AnswerRating=1&xid=50373&query=bike&prev=QA%2520&vid=2575374
http://www1.askme.com/SearchResults.asp?pm=va&cid=852&xShowNew=1&QA=on&AnswerRating=1&xid=50373&query=bicycle&prev=QA%2520&vid=907080
--
Paul Doherty, CNA, CNE, MCP+I, MCSE, A.A.Sc., B.A.
http://members.home.net/iqueue
Home of PC DiskMaster and other Windows utilities
Rating : 5
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QAId : 3044361
Asker : mbishop@...
Subject : physics
Private : No
Question : How long does it take light to travel from the sun to the earth?
Answer : About 8 minutes...
Here is a table of distances and times for the planets:
http://sohowww.nascom.nasa.gov/explore/faq/astronomy.html#LIGHT_TIME_TO_PLANETS
--
Paul Doherty, CNA, CNE, MCP+I, MCSE, A.A.Sc., B.A.
http://members.home.net/iqueue
Home of PC DiskMaster and other Windows utilities
----------------------------------------------------------------------
QAId : 3086744
Asker : ph_aser
Subject : vision
Private : No
Question : If in subtractive colour (i.e. mixing of paints) the resulting colour
is determined by the overall reflective properties of the paints involved, then
how come black isn't the result of a mixture of two or more different colours?
For example if red paint reflects red light and absorbs the other frequencies of
light and yellow reflects only yellow and absorbs the others, then surely when
the two are mixed the red pigment will absorb yellow light and the yellow will
absorb red resulting in no light being reflected. Can you explain why this is
not so?
Answer : It is not so because you have mistakenly identified red as a primary
subtractive color when it is not. Red is a primary *additive* color. The three
primaries for subtractive coloring (as in a printing press) are:
yellow
cyan
magenta
Where each overlaps another a color is produced by the mechanism you described.
For example:
When yellow and cyan overlap the resultant (left over) color is green. When
magenta and yellow are used the result is red. Only when white light passes
through all three of these subtractives are all frequencies removed for a result
of black.
--
Paul Doherty, CNA, CNE, MCP+I, MCSE, A.A.Sc., B.A.
http://members.home.net/iqueue
Home of PC DiskMaster and other Windows utilities
----------------------------------------------------------------------
QAId : 3087861
Asker : tony92
Subject : ANSI Lumens
Private : No
Question : What is the formula for converting footcandle to ANSI Lumens?
I have a Illuminometer but it does not indicate lumens on the meter display.
tony@avpres.org
Answer : This site has a good discussion on it:
http://www.a1.nl/phomepag/markerink/lumencan.htm
--
Paul Doherty, CNA, CNE, MCP+I, MCSE, A.A.Sc., B.A.
http://members.home.net/iqueue
Home of PC DiskMaster and other Windows utilities
----------------------------------------------------------------------
QAId : 3099646
Asker : poorpg
Subject : Time , 24 hours?
Private : No
Question : Why there is 24hrs a day, but not ten instead?
Answer : Cecil Adams has already answered this one better than I... (the
following taken from http://www.straightdope.com/classics/a1_125.html):
Dear Cecil:
My question arises from the fact that my kitchen happens to have both a boldly
appointed digital clock and an old noisy analog thing my grandmother bought
around 1940. I was delighted to discover quite by accident one bloodshot night
that I could read the time on granny's clock from a far greater distance, and
with much less light, than I could its digital counterpart. However, it occurred
to me that were it to have been divided into eight equal sections, like a
compass, reading it would be even less ambiguous. There is an obvious length to
our day, but pray tell where is it written that it have 24 divisions called
hours? --P.P., Chicago
Dear P.:
Well, I could always find it in the back of the Growth in Arithmetic book, along
with 16-1/2 feet to the rod. But maybe you had the abridged edition. In any
case, we have the Babylonians to thank for our present system of timekeeping.
The number 12 held mystical significance for the ancients, owing to the fact
that there were generally 12 full moons a year, and so they divided day and
night into 12 parts each. The number 60, apart from being a multiple of 12, is
evenly divisible by more integers than any lesser number, and thus was useful
for dividing hours into minutes and seconds without the distraction of
fractions.
The Babylonian calendar had 12 months of 30 days; since this left five days
unaccounted for each year, every sixth year they repeated the month of Adar. The
Romans, of course, introduced the present cockeyed system of 28-, 30-, and
31-day months.
While the Babylo-Roman method has a certain primitive charm, it does not make
for ease of calculation, and there have been several attempts over the years to
devise a more rational system. Perhaps the most famous of these was the social
experiment conducted during the French Revolution.
In 1793, in an effort to sweep away the superstitious associations of the old
method of timekeeping (you know how revolutionaries are), the French National
Convention established a new calendar with 12 months of 30 days each, followed
by five (six in leap years) "complementary days," which belonged to no month.
Each month was divided into three 10-day "decades," and each day into two
sections of 10 hours each. The hour was further divided into 100 "decimal
minutes," which were in turn divided into 100 "decimal seconds."
The year began on the autumnal equinox, which happened to be the anniversary of
the foundation of the Republic. Each month was given a descriptive name, e.g.,
Thermidor, July 19-August 17, "month of heat." Each day was also given its own
name, some of which were less inspired than others, e.g., Eggplant, Manure,
Shovel, Gypsum, Billy Goat, Spinach, and Tunny Fish. Even the French couldn't
seriously have felt these represented a significant advance over old faves like
Maundy Thursday. Also, on a more practical front, who wants to work a ten-day
week?
Nontheless the French public made a valiant effort to implement the new system,
going so far as to manufacture watches with concentric 10- and 12-hour dials.
But ultimately the task proved to be beyond them. In 1806, after 13 baffling
years of missed dentist appointments and overdue library books, they abandoned
the revolutionary calendar. This was the only known defeat of Progress in the
modern era prior to the establishment of the Illinois General Assembly. Gives
you pause, when you think about it.
--CECIL ADAMS
--
Paul Doherty, CNA, CNE, MCP+I, MCSE, A.A.Sc., B.A.
http://members.home.net/iqueue
Home of PC DiskMaster and other Windows utilities
Rating : 5
----------------------------------------------------------------------
QAId : 3135340
Asker : Dave_Va_1999
Subject : windows2000,NT, and win 98
Private : No
Question : Hello
I have a Dell 633 MHZ computer with 20 GB hard drive and 128MB RAM. I have made
3 partitions on the hard drive(2GB FAT 16, 8 GB NTFS, and 8GB NTFS). I have
WIN98 on the first partion and now I want to install NT workstation 4.0 on the
second partion and Windows 2000 on the 3ed partition, is this possible? I tried
it several times, but if I get NT to work windows 2000 doesn't work and if i get
windows 2000 to work NT doesn't work. Is it possible to install all these 3
operating systems in one machine? if it is can you please tell me how?
Thanks
p.s: I installed service pack 5 on NT workstation.
Answer : Here is a site with blow-by-blows for installing Windows 2K in tandem
with other MS operating systems...
http://www.winmag.com/windows/guides/win2000/
--
Paul Doherty, CNA, CNE, MCP+I, MCSE, A.A.Sc., B.A.
http://members.home.net/iqueue
Home of PC DiskMaster and other Windows utilities
Rating : 2
----------------------------------------------------------------------
QAId : 3143789
Asker : ssheena
Subject : magnetic elevatation
Private : No
Question : whats is magnetic elevatation? it has some priciples to do with
electric trains and roller coasters. but how does it work and what is it?
Answer : It's really a simple concept. Try playing with some bar magnets (or
just remember when you have done so previously). Each magnet has a north and
south pole. Opposite poles (like the north on one magnet to the south on the
other) attract each other. Like poles (south to south, for instance) repel. This
is the essense of a "maglev" train as they are called as the repulsive magnetic
force is used to elevate the train above the track. This makes for very fast
trains (some over 300MPH) that have near to no friction or noise generated (plus
no pollution to speak of, other than that used to generate the admittedly large
amount of electricity such trains consume)). See this page for information and
images on these maglev trains:
http://www.abcnews.go.com/sections/tech/DailyNews/maglev990624.html
--
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 : 3149760
Asker : Dave_Va_1999
Subject : Win98,NT, and Win 2000
Private : No
Question : pauldoherty gave this response on 9/20/2000:
Here is a site with blow-by-blows for installing Windows 2K in tandem with other
MS operating systems...
http://www.winmag.com/windows/guides/win2000/
Hello again
Thanks for the tip.
I went to that site and couldn't find a stright answer to my question. Is it
possible to install Win98, NT 4.0, and Win 2000 all in one machine.
thanks again.
Answer : Yes it should work fine...
Install in this order:
98
NT
Win 2K (install to separate partition with "new install" option)
--
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 : 3181167
Asker : penney_4
Subject : electrons
Private : No
Question : Where did electron get its name?
Answer : Here's some info on the electron:
http://encarta.msn.com/find/Concise.asp?z=1&pg=2&ti=761558264
1856 - Physicist Sir Joseph J. Thomson is born in Cheethan Hill, England. He
discovered the electron in 1897, and received the 1907 Nobel Prize for Physics.
--
Paul Doherty
http://members.home.net/iqueue
Rating : 3
----------------------------------------------------------------------
QAId : 3181718
Asker : aljufri2
Subject : question
Private : No
Question : what is cold fusion ?
is it myth or reality?
what is the chemistry point of view about it ?
what is the physics point of view about it?
if we comporsion between them can we answer this question "what would be the
other sources of energy,I mean"Oil versus what???"
Answer : Cold fusion is the idea of getting light elements like hydrogen to
combine to form heavier elements that have a lower mass-per-nucleon. A small
percent of the mass differential is converted to energy.
The problem with fusion is that when you try to fuse nuclei together the only
items inside the nucleus with a charge are protons. Protons have a positive
charge and *repel* other protons. So to get two nucleuses to bond means you have
to overcome that resistance. Usually to do this requires a great amount of heat
to get the atoms moving at a very high rate of speed. Only with these tremendous
speeds can the repulsive force be overcome.
Cold fusion is an attempt to produce this effect by chemical means. Unless
someone is exceptionally clever at it I'm not sure it's all that viable of a
concept. Only time will tell.
Competing forms of power generation are nuclear fission, coal, natural gas,
hydroelectric, thermic, solar, wind... I may be missing a few but that's
probably all the big ones.
--
Paul Doherty, CNA, CNE, MCP+I, MCSE, A.A.Sc., B.A.
http://members.home.net/iqueue
Home of PC DiskMaster and other Windows utilities
Rating : 5
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QAId : 3220253
Asker : Friiends
Subject : Hi!!!!!!
Private : No
Question : can u tell me a little information on wat anti-matter is?
thanks a lot, Asheigh
Answer : Here is Cecil's answer on the subject (always good for info and a
laugh)...
http://www.straightdope.com/mailbag/mantimatter.html
--
Paul Doherty, CNA, CNE, MCP+I, MCSE, A.A.Sc., B.A.
http://members.home.net/iqueue
Home of PC DiskMaster and other Windows utilities
----------------------------------------------------------------------
QAId : 3232024
Asker : ata6x
Subject : Physics, Biology, and Projectile Motion
Private : No
Question : There is a field that links biology and physics and also uses
projectile motion. What is it?
Answer : It's called NASA (space exploration)... ;-)
--
Paul Doherty, CNA, CNE, MCP+I, MCSE, A.A., B.A.
http://members.home.net/iqueue
Home of PC DiskMaster and other Windows utilities
Rating : 5
----------------------------------------------------------------------
QAId : 3239956
Asker : emarlo
Subject : Physics Question
Private : No
Question : I am a student at BU in an Elementary physics class. I have one
problem that I can't seem to get an answer to. The problems reads as follows:
At serve, a tennis player aims to hit the ball horizontally. What minimum speed
is required for the ball to clear the .90m high net about 15.0m from the server
if the ball is "launched" from a height of 2.50m? Where will the ball land if it
just clears the net (and will it be "good" in the sense that it lands within
7.0m of the net)? How long will it be in the air?
I would greatly appreciate your help on this problem
Thanks,
emarlo
Answer : OK, here we go.
distance from server to net - 15m
height of net - .9m
height of ball at horizontal launch - 2.5m
maximum distance travelled for "good" shot - 22m (15m + 7m on other side of net)
The first thing we need to find is how far the ball can fall before it will not
clear the net. It's starting at 2.5m and will not clear after the level of the
net, .9m, so we simply subtract .9 from 2.5m and get 1.6 meters. This is the
maximum distance we can fall before crossing the net.
So now we need to know how long that fall (1.6m) takes. Since the gravitational
acceleration is unaffected by our shot speed we can safely calculate this time
by this:
1/2gt^2 = 1.6
(1/2 * g (9.8m/sec))
4.9*t^2 = 1.6
(divide both sides by 4.9)
t^2 = .33
(take the square root of each side)
t = 0.57 seconds to fall 1.6m
Now that we know the time to fall 1.6m we can calculate how fast our ball must
travel to cover the 15m from server to net so the ball will cross the net.
0.57 * x = 15m
(divide both sides by .57)
x = 26.32 m/sec
So we must strike the ball at 26.32m/sec speed in order to arrive at the net
height in our required time interval of .57 seconds.
Now that we know part of the answer (our minimum shot speed) we can calculate
how far the shot will travel at that speed before it hits the ground, and where
it will be when it hits. We do this by measuring the time it takes for the full
initial ball height (2.5m) to be lost:
1/2gt^2 = 2.5m
(1/2 * g (9.8))
4.9 * t^2 = 2.5m
(divide both sides by 4.9)
t^2 = .51
(take the square root of both sides)
t = .71 seconds
This is the time it will take from launch until the ball hits the ground. Now
all we need to do to find the distance travelled is multiply this time by our
shot velocity:
.71 * 26.32 = 18.69m
So our ball will travel 18.69m before hitting the ground. The full distance the
ball can travel and still be inside the "good" range for a serve is 22m so our
shot will be good, and will strike 3.9m away from the net on the other side of
the net (18.69m - 15m to net = 3.9 more to travel).
--
Paul Doherty, CNA, CNE, MCP+I, MCSE, A.A., B.A.
http://members.home.net/iqueue
Home of PC DiskMaster and other Windows utilities
Rating : 5
Rating : 5
----------------------------------------------------------------------
QAId : 3290328
Asker : kkwan82
Subject : college studying
Private : No
Question : I just entered college this year and am starting to have problems
with my school work already. I would like if you give me some advice on how I
should go about studying for my courses.
Physics
I was able to do physics last year in high school (high school physics). As I
entered into my physics class just recently in college, I felt that I would be
able to do well. However, I just can't seem to handle the quiz and test
problems. The professor purposely makes the questions tricky and the wording of
the problems are awkward. I'm not sure if I should refer to the textbook.
Usually, I don't read the textbook. I just read and do problems in my Schaum's
Outline of College Physics review book. However, the review book just doesn't
seem to cut it anymore since the problems in the review book are very general
and not tricky. I'm not sure what I can do to help myself face physics like
this. Can you give me any suggestions or tips?
Thanks very much for your help. I appreciate it greatly.
Kenneth S. Kwan
kkwan82@hotmail.com
Answer : Since I don't know your strengths or weaknesses I would suggest either:
1) Getting a tutor in the subject.
2) Dropping the class this semester and take it at another time from a different
professor.
--
Paul Doherty, CNA, CNE, MCP+I, MCSE, A.A.Sc., B.A.
http://members.home.net/iqueue
Home of PC DiskMaster and other Windows utilities
Rating : 2
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QAId : 3353077
Asker : mothy75
Subject : I swear all are my own questions
Private : No
Question : Dear Pauldoherty,
I promise and swear all questions I asked you are from myself, not any one is
copied from any book. If you don't feel comfortable to answer me, it is fine.
But I have to clarify again all questions are coming from my thoughts after
reading a introduction of a Computer Network book.
Thanks
Tim
Answer : OK... I just tend to avoid those that look like homework. Ask again and
I will see if I can help.
--
Paul Doherty
http://members.home.net/iqueue
----------------------------------------------------------------------
QAId : 3428257
Asker : bay37
Subject : static electricity while refueling
Private : No
Question : I know that fires and explosions have occurred while filling portable
gas cans sitting in pickup truck beds. Most gas stations now have warnings about
how to prevent this. My question: I refill with gas a 26 gallon "Gas Dock" with
wheels for marine use. I load it in back of van, fill with gas and slide it down
the rear bumper of van. When filled, it is too heavy to lift into van.
Can I safely dissipate any static charge while it is still in the back of the
van by connecting a jumper cable to metal valve of "gas dock" and letting the
other end of the jumper cable rest on the pavement? I plan to do this before and
during the filling operation.
Thank you!
Answer : Cement is not terribly conductive in my understanding, so I wouldn't
count on this - plus there is no guarantee that the cement will actually
"ground" you (no pun intended... well, ok maybe a little pun intended ;-). If
you are curious about this you could hook up an Ohm meter and measure before and
after *on an empty gas can* to see if it actually eliminates the juice or not.
I'd do that before I'd be filling that gas can...
--
Paul Doherty
http://members.home.net/iqueue
----------------------------------------------------------------------
QAId : 3455880
Asker : mellanium_mazhar@...
Subject : scalar & vector
Private : No
Question : define equilibrium & its all states.
define centre of gravity & method to find the centre of gravity of irregular
shape bodies.
Answer : Equilibrium is a state of balance where forces are counteracted in such
a way that accelerations are not taking place.
Center of gravity (also called center of mass) is the central point of the mass
of an object. It is considered to be the point that "controls" an objects'
state. A basketball for instance has a center of gravity in the center of the
hollow space inside, where there is nothing but air. For irregularly-shaped
objects (say a strangely-shaped rock) you can find the center of gravity by
simply hanging the object from a string *from more than one point* and simply
seeing where the vertical lines converge. Draw a line down from the string
through the object perfectly vertical towards the ground in both cases - that
intersection is the center os gravity.
--
Paul Doherty
http://members.home.net/iqueue
----------------------------------------------------------------------
QAId : 3470532
Asker : bsv3
Subject : Why would seawater below 32 degrees F remain liquid?
Private : No
Question : Why would seawater below 32 degrees F remain liquid?
Answer : Probably because it has so much salt and is not "pure" water.
--
Paul Doherty
http://members.home.net/iqueue
----------------------------------------------------------------------
QAId : 3470557
Asker : xolildorisox
Subject : physics
Private : No
Question : how fast do you have to travel to escape earth's gravity
Answer : A launch speed of 11km/sec is required to escape the Earth's
gravitational pull.
A launch speed of 8km/sec is required to orbit an object around the Earth.
--
Paul Doherty
http://members.home.net/iqueue
----------------------------------------------------------------------
QAId : 3477768
Asker : Anonymous
Subject : acceleration of a falling object
Private : Yes
Question : I did an experiment to test the acceleration due to gravity. A paper
tape was attached to a machine that held an object of some mass. When the object
was released and allowed to fall, the paper tape was marked every 1/40th of a
second. I found the distance the object traveled in each interval using a metric
ruler. Once I got my data and the results, I calculated the acceleration. It was
close to 9.4. The acceleration of a falling object is supposed to be -9.8m/s^2.
What could have caused the error in my experiment? Also does the velocity of an
object always increase when it’s falling and does the acceleration always stay
the same?
Thanks for your help. Please reply soon.
Answer : Was there anything attached to the object that may have impeded it's
acceleration (perhaps the apparatus that was marking the tape)? Was the object
massive enough that air resistance was negligible?
The velocity of a falling object does continue to increase throughout a fall
*until* terminal velocity is reached. TV is the fastest an object can freefall
in air. That point is reached when the object is falling fast enough that wind
resistance (a function of surface area) is equal to the objects weight. In the
absence of air an object would continue to accelerate until it struck the
ground. The accelerating force is not entirely uniform as gravitational pull
falls off with the inverse-square law so as you approach the Earth the
graviational force is greater, and so is your acceleration.
--
Paul Doherty
http://members.home.net/iqueue
Rating : 5
----------------------------------------------------------------------
QAId : 3488135
Asker : emarlo
Subject : Rotor ride
Private : No
Question : This is an interesting problem, but I am having problems figuring it
out:
In a "Rotor-ride" at a carnival, people pay money to be rotated in a vertical
cylindrically walled "room." If the room radius is 5.0m, and the rotation
frequency is .50 revolutions per second when the floor drops out, what is the
minimum coefficient of static friction so that the people will not slip down? Is
there really an outside force pressing people against the wall? If so, what is
the source?
I would appreciate your help greatly.
emarlo.
Answer : I'm not sure how to calculate the friction coefficient.
As for there being a force from outside, no there isn't. The "force" that is
holding the people to the sides of the cylinder is their own velocity, in the
form of centripetal acceleration. Since the cyclinder is a curved surface it
doesn't allow their bodies to travel the direction they'd like to travel (a
straight line) so their bodies are constantly undergoing acceleration
(acceleration is a change in velocity - which includes both speed and direction
of travel). the force of the surface resisting their attempts to pass through it
:-) is the force that keeps them from sliding down it's surface.
--
Paul Doherty
http://members.home.net/iqueue
Rating : 4
----------------------------------------------------------------------
QAId : 3491269
Asker : Anonymous
Subject : heat/a/c
Private : No
Question : is there anywhere on the internet that i can get schematics on
various a/c and heating units?
Answer : Here's some...
http://www.repairfaq.org/sam/samschem.htm
--
Paul Doherty
http://members.home.net/iqueue
----------------------------------------------------------------------
QAId : 3539145
Asker : hyde_jackel
Subject : FORCE AND MOMENTUM
Private : No
Question : Hi, heres my question....
You are standing on a log and a friend is trying to knock you off. He throws the
ball at you. You can catch it, or you can let it bounce off of you.
Which is more likely to topple you, catching the ball or letting it bounce off?
thanks
HJ
Answer : Letting it bounce off you is more likely to dislodge you from the
log...
The ball has a certain momentum as it travels towards you (imparted by your
friend). When the ball arrives if you catch it the full force of that momentum
is imparted to you (by the force required to stop the ball's flight). If instead
you allowed the ball to strike you and bounce off the ball has gone from *having
momentum in one direction, to now having momentum in the opposite direction, and
the only place that new "negative" momentum can have come from is you*. So the
effect of letting the ball bounce is that *more* momentum (in the ball's
original direction of travel) is imparted to you than if you had simply caught
it.
--
Paul Doherty
http://members.home.net/iqueue
Rating : 5
----------------------------------------------------------------------
QAId : 3587047
Asker : thinkwhy
Subject : fate and the quantum
Private : No
Question : Do you have any idea about the relation between the Quantum physics
and fate ?...
Answer : Are you questioning whether fate can exist due to the inability to
predict? If so I might respectfully suggest that our inability to predict does
not preclude that something beyond our ken dictates our course...
--
Paul Doherty
http://members.home.net/iqueue
----------------------------------------------------------------------
QAId : 3626795
Asker : mindak01@...
Subject : the physics of audio speakers
Private : No
Question : I have a report to do on the physics of audio speakers. I looked
around and I couldn't find any sites that would tell me. So do you know the
forces involved, velocities, properties, laws of motion, and that kinda thing
that goes along with audio speakers? Thanks. Melinda
Answer : I don't know of any sites that discuss this, but the main things I
think you'll want to think about are:
Newton's Laws (magnet/speaker-coil movement)
wave motion (longitudinal sound waves)
biomechanical movement of the eardrum/canal
--
Paul Doherty
http://members.home.net/iqueue
----------------------------------------------------------------------
QAId : 3724647
Asker : hockey23
Subject : terminal velocity?
Private : Yes
Question : A co-worker of mine threw a penny off the empire state building the
other day. Please don't ask me why. Could the force of the penny falling 114
stories kill someone at ground level? I thought that it would reach terminal
velocity and the force would not be great enough, but other people think that
the force would be great enough to kill someone, or severely injure someone on
the ground. Can you explain?
Answer : A penny is too light and has too much surface area - as you said it
will reach it's terminal velocity and carry on at that speed until it hit the
person. And the speed will be relatively slow because of the penny's light
weight. I'd estimate a terminal velocity of around 30m/sec which would hurt like
heck, and may be enough to crack your skull, but probably not, and almost surely
not enough to kill you.
Answer : One other thing - please do not ask normal questions like this as
"private" questions. Doing so deprives others of reading them and defeats part
of the collaborative nature of AskMe.com...
Thanks,
Paul
Rating : 5
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QAId : 3746893
Asker : icollaboDotCom
Subject : DateSet
Private : No
Question : Mr.pauldoherty,
I have had your program work successfully in test 2 times, Once on Win 2000 and
on Win 95. I am now on trying to install it on a Windows NT Server machine and
having all kinds of problems. I have done the follwing:
1. Installed the DATESET.EXE into C:\WINNT\system32
2. I have tried to test the following code on the machine
dateset
c:\mydate.bat
ren C:\WINNT\Profiles\Administrator\Desktop\t.txt
C:\WINNT\Profiles\Administrator\Desktop\t.%MYDATE%
3. The program is running throught the process the Dos output as I run the batch
file resembles
C:\Byp>bypbkup.bat
C:\Byp>dateset
C:\Byp>c:\mydate.bat
When I run the following, I get an error message that:
"The syntax of the command is incorrect." It appears to be referencing "call
c:\mydate.bat"
dateset
c:\WINNT\system32\dateset.exe
call c:\mydate.bat
cd c:\
ren C:\WINNT\Profiles\Administrator\Desktop\t.txt
C:\WINNT\Profiles\Administrator\Desktop\t.%MYDATE%
Adding "c:\WINNT\system32\dateset.exe" provides the same results as the first
scenario? Here is that batch file...
dateset
c:\WINNT\system32\dateset.exe
c:\mydate.bat
cd c:\
ren C:\WINNT\Profiles\Administrator\Desktop\t.txt
C:\WINNT\Profiles\Administrator\Desktop\t.%MYDATE%
I am totally confused? HEEELLLPPPPPP!!!!
-Brad
Answer : Try using the exact same path and filenames as in Windows 95 (where it
worked) under NT - if it still fails it is something about NT and we can go from
there.
--
Paul Doherty
http://members.home.net/iqueue
FUQuestion : AHHHHHHHHHHHHHH,
Anything you see wrong here? Gives me a message that: The syntax of the command
is incorrect...
This is on W2000
c:\WINNT\SYSTEM32\dateset.exe
call c:\mydate.bat
ren C:\Documents and Settings\Law\Desktop\pfboae.bak C:\Documents
Settings\Law\Desktop\pfboae.bak.%MYDATE%
Answer : You still need the quotes around the long paths:
ren "C:\Documents and Settings\Law\Desktop\pfboae.bak" "C:\Documents and
Settings\Law\Desktop\pfboae.bak.%MYDATE%"
Also you were missing the "and" in the second parameter.
And I would also do as I suggested before and CD to the directory before
renaming, like this:
c:
cd "\Documents and Settings\Law\Desktop"
ren pfboae.bak pfboae.bak.%MYDATE%
--
Paul Doherty
http://members.home.net/iqueue
Rating : 5
----------------------------------------------------------------------
QAId : 3758105
Asker : rombe3jr
Subject : Rainbows
Private : Yes
Question : Can rainbows be recreated by man without the sun, but by artificial
light? If so could you tell me how it was done?
Answer : Any light source behind you, with water vapor in front of you, can make
a rainbow. The chances of us having lights powerful enough to generate a
sky-stretcher like a full-blown rainbow are not likely, but the same concept
applies. You can create a rainbow with a flashlight and a prism.
FUQuestion : Hey I really appreciate your answer. But I am very interested in
creating a minerature rainbow myself. Is there any resource that you know of
that could guide me in this process?
Answer : I don't know of any web sites that detail it - try searching from:
http://www.queryserver.com
(general search)
with terms like rainbow and flashlight.
I would take a flower misting device and set it up and running, then stand back
several feet and shine a Q-Beam (strong large flashlight) at the water vapor
from different angles until you see the rainbow.
--
Paul Doherty
http://members.home.net/iqueue
----------------------------------------------------------------------
QAId : 3765324
Asker : Anonymous
Subject : chemistry question
Private : No
Question : what is the wavelength and frequency of infa-red light
Answer : There is a nice graphic with different frequencies of light (including
infrared) and their corresponding wavelengths here:
http://www.ozemail.com.au/~swadhwa/chap2lec1.html
Infrared appears to be from 10^12 to 12^14 Hertz in frequency.
--
Paul Doherty
http://members.home.net/iqueue
----------------------------------------------------------------------
QAId : 3797022
Asker : Anonymous
Subject : I need help quickly!
Private : Yes
Question : I am doing a science fair project on light absorption and reflection
on different colored popsicle stick cabins! My background research is due on
Tuesday, nov. 7, and I can't find ANYTHING!! PLease help me... I am despersate!
Tell me everything you know about the subjects or give me resources where I can
find the info!
Answer : Any physics book will have lots of material on this - the concepts of
light absorption are fairly easy.
----------------------------------------------------------------------
QAId : 3821745
Asker : mandiesr02@...
Subject : light primaries
Private : Yes
Question : 1. What are light primaries?
2. What is the difference between painters and printers primaries?
3. What happens when contrasting hues are mades similiar?
Answer : 1. "Primaries" are those base frequencies of light (or paint) that,
when combined, produce (in the case of light) or remove (in the case of
inks/paints) all the visible frequencies of light. Example - the primaries for
visible light are red, green and blue.
2. As far as I know since both are subtractive there is no difference between
paint and ink primaries.
3. I'm not sure what you are asking here - more detail please.
--
Paul Doherty
http://members.home.net/iqueue
----------------------------------------------------------------------
QAId : 3826318
Asker : ayaz05
Subject : How to determine distance
Private : No
Question : Reply me that how i can determine distance between to cities by using
their latitudes and longitudes.
Bye.
Ayaz.
Answer : This may help:
Taken from - http://www.comptons.com/encyclopedia/ARTICLES/0100/01054720_A.html
"A degree of latitude can easily be changed into miles. Since the circumference
of the Earth is roughly 25,000 miles, the length of each degree of latitude is
about 69 miles (1/360 of 25,000 miles). Degrees of latitude vary a little in
length--the variation between the shortest and the longest is less than a
mile--because the Earth is not a perfect sphere but is flattened slightly toward
the poles and bulges slightly around the equator (see Earth). The length of a
degree of longitude, however, varies from about 69 miles at the equator to zero
at the poles, where the meridians come together."
--
Paul Doherty
http://members.home.net/iqueue
----------------------------------------------------------------------
QAId : 4105552
Asker : krtina03
Subject : Psysics
Private : No
Question : Hi, how are you today? Why did scientists use a vacuum to determine
acceleration of a falliing object?
Answer : Because when objects fall through a medium, such as air, their
acceleration (and top speed) are affected, based on their volume and mass. If
you had a bowling ball and another ball of exactly the same size but made of
plastic and hollow and dropped both, the bowling ball will reach a higher top
speed than the other ball. Both are accelerated by the same force of gravity,
and each will accelerate at roughly the same speed up to that maximum. That
maximum is called "terminal velocity" and is the fastest speed of freefall for
that object. Terminal velocity is reached when an object has attained a speed
such that the wind resistance encountered in the downward direction is equal to
the object's weight. Since the real bowling ball has a much higher mass than the
hollow one (even though both have equal surface areas - wind resistance being a
funtion of surface area) it will attan a higher terminal velocity.
In the same experiment absent of air both balls will continue to accelerate at
exactly the same speed, whether their masses or volumes are the same or not. The
classic experiment confirming this was when the first lunar astronauts filmed
themselves dropping a hammer and a feather at the same time and seeing both
accelerate and hit the ground at the same time.
--
Paul Doherty
http://members.home.net/iqueue
----------------------------------------------------------------------
QAId : 4122610
Asker : Anonymous
Subject : Light waves
Private : Yes
Question : Light travels threw air and well also in a vacum but here is my
question. My question is that if it travels threw a vacum it doesn't need a
medium but what if there is a medium in a vacum that can not be removed?
That means it needs a medium.
Am I right?
What theory says that it doesn't need a medium when in terms it travels in a
wave way.
Light waves.
Thanks
Answer : No theory is required to demonstrate that light requires no medium
since we get tons of light across the void of space from our Sun. Before we
could travel out into space there were theories of an "ether" that was required
for light tranmission but the Michelson-Morley experiment disproved that
hypothesis.
Light travels *both* as a wave and as a particle (or rather I should say it can
interact as both). That is one of the paradoxes of light.
--
Paul Doherty
http://members.home.net/iqueue
Rating : 5
----------------------------------------------------------------------
QAId : 4194018
Asker : Socmomcab
Subject : Collisions
Private : Yes
Question : I don't understand this question. Could you please help me? THanks
A 2-kg ball is travelling down a pool table at 10m/s. It proceeds to collide
with 2 balls that are sitting side by side that also have a mass of 2-kg with
the cue ball striking the other two simultaneously (i.e. it strikes between the
two balls). What is the velocity of the three balls after the collision? Please
give both the magnitude and direction for each velocity. (Assume all the balls
have the same radius.)
Answer : It sounds like you have a rolling cue ball that is striking two other
balls that are at rest and touching and aligned perfectly perpendicular to the
path of the cue ball. The question wants to know the resultant direction and
speed of travel of all three balls after the collision. I would expect the two
balls currently at rest will be travelling with some speed at 45 degree angles
to the direction of the cue ball.
--
Paul Doherty
http://members.home.net/iqueue
Rating : 3
----------------------------------------------------------------------
QAId : 4218296
Asker : Anonymous
Subject : Rainbows
Private : Yes
Question : What shape can rainbows not look like?
How come rainbows can be in different shapes?
Thanks bye
Answer : Please do not ask questions in private if they are not of a private
nature. This is a general question, and not of an embarrassing nature. Marking
it as private detracts from the value of our interaction to others as they
cannot read it under any circumstance.
Rainbows are only seen at specific angles from the viewer to the water, and from
the water to the light source (usually the sun). The typical rainbow is a
half-circle. A full rainbow would be a full circle (replacing the bottom half
that is usually where the ground is).
--
Paul Doherty
http://members.home.net/iqueue
Rating : 5
----------------------------------------------------------------------
QAId : 4230647
Asker : zuetz
Subject : physics
Private : No
Question : Is the thoery of relativity proved?
Answer : As for the particularly mind-bending portion of relativity I expect you
are ferring to (the time dilation effect) yes it has been proven. Two atomic
clocks that are highly accurate were synchronized - one was left on the Earth
and the other was flown in airplane shipments for some period of time. The
relative motion between them should produce a time difference between them per
the theory of relativity. Since the speeds were not appreciable when compared to
the speed of light (speeds closer to light have exponentially greater time
dilation effects) the difference would be still be easily measurable with such
accurate clocks. Since the clock that rode on the airplanes was in motion
relative to the clock on Earth it was expected that the moving clock's
transpired time would be less than the Earth-bound clock and it was found to be
so, thus confirming the theory's predictions.
--
Paul Doherty
http://members.home.net/iqueue
----------------------------------------------------------------------
QAId : 4230717
Asker : jontha_au
Subject : fridge magnets
Private : No
Question : Why dont fridge magnets have poles?
Answer : They do have poles, they are just not physically apparent like in a bar
magnet. Even the smallest magnetic "domain" (smallest magnetic component that is
the basis for all magnets) has it's own north and south pole. It is only by
virtue of the fact that some materials have the majority of their magnetic
domains facing the same direction that those materials are magnets in the first
place. Notice that if you take an existing magnet and heat or strike it you will
diminish it's magnetic strength. This isn't because there is less magnetic
energy than before - it's because you have dislodged and misaligned some of the
internal magentic domains so their force no longer adds to the aggregate force
(their pull is no longer properly aligned to add to the overall force).
--
Paul Doherty, CNA3/CNE_4/CNE_IW/CNE_5/MCP/MCSE/A.A.Sc./B.A.
http://members.home.net/iqueue
Home of PC DiskMaster and other Windows utilities
----------------------------------------------------------------------
QAId : 4230832
Asker : sweet_jul
Subject : What heats faster water or sand?
Private : No
Question : What heats faster water or sand?
Answer : I must disagree with my esteemed fellow expert DanMan.
Sand will heat faster than water. "Specific heat" is ameasure of a materials
resistance to change of temperature. Water has a very high specific heat,
meaning it has a lot of "temperature inertia" for lack of a better term. If it
is cold it takes a lot to heat it - if hot it takes a long time to cool. This is
the primary reason we use water in all the ways we do. Hot water bottles stay
warm longer than the same vessel filled with another liquid. Radiators of cars
absorb massive amounts of heat. The best example of this phenomenon that even
uses the two materials you've asked about is the beach. In the morning before
the sun rises the water and sand are at or near the same temperature. When the
sun comes up the sand quickly warms, making the sand burn your feet, even before
the water is warm enough to swim in (this is due to sand's low specific heat -
it doesn't resist changes in temperature well). All during the day the sand is
warmer than the water, and all day the water is absorbing more and more radiant
energy (light) and warming more and more but likely never equalling the sand's
temperature. Then as the sun goes down the sand, having a low specific heat,
cools quickly, while the water remains relatively warm throughout most of the
night. You can easily demonstrate this entire effect by observing the breezes at
the beach. During the day, when the sand is warmer than the water, the hotter
air above the sand rises, to be replaced by the cooler air from over the ocean.
This produces breezes that blow in from the ocean. At night the water stays
warmer than the sand which quickly cools and the breeze is reversed and blows
out to sea.
--
Paul Doherty, CNA3/CNE_4/CNE_IW/CNE_5/MCP/MCSE/A.A.Sc./B.A.
http://members.home.net/iqueue
Home of PC DiskMaster and other Windows utilities
Rating : 5
----------------------------------------------------------------------
QAId : 4238232
Asker : _merlyn_
Subject : why.....?
Private : Yes
Question : Hi !
My name is Ameya and am relatively new to askme as an expert on this category.
Have just been exposed to a number of questions and have answered most of them.
Before I get going on further I thought it would be a good idea to get some
perspective from you.
Hoping you can share your thoughts and feelings on the following questions that
burn away in my mind….. out of curiosity and wonder that so many of you experts
are actually here to advice and counsel all the people asking queries.
1. What are the advantages of becoming an expert on this category? i mean, what
is it that makes you all spend time and energy answering all these questions?
What is it that you find rewarding?
2. Is there any other place where you are an expert and what are the relative
advantages here?
many thanks and warm regards,
Ameya
Answer : Hi Ameya...
1 The only advantage to becoming an expert in this (or any other) category is it
makes it more ikely that (if you are highly ranked in the category) that you
will receive an award if the category is picked by AskMe.com during one of their
prize selections. As for myself I have won I think 4 or 5 category awards and 2
quarterly awards (cash and tshirts for each) but I began and continue answering
questions not for that. When I started in Jan 2000 there were no awards at all.
It was only in March or April that they began that and with it came some less
than stellar new experts along with it.
I answer the questions for the following reasons:
a) I like to help people
b) It keeps me sharp in areas of interest
c) I enjoy the recognition
d) it's fun
2) I do not answer questions on any other websites, although I do participate in
forum dicussions. Other expert sites will pay you for your information. These
sites, however, are not as attractive for me as they usually involve you being
made available by phone to someone with a problem (this is usually for computer
experts). The problem with this is that, unlike AskMe, the questions and answers
are not known so there is no huge database of knowledge like there is here. That
is another advantage for me here - I build up a large repository of questions
(almost 2000 so far!) that I've answered that I can go back and look at later.
My categories of expertise:
http://www.askme.com/viewprofile.asp?xid=50373
Best of luck to you!
--
Paul Doherty
http://members.home.net/iqueue
----------------------------------------------------------------------
QAId : 4246249
Asker : cindy_lens
Subject : stop print cover page
Private : No
Question : Hi
After downloading and installed HP printer from hp.com onto SUNS Sparc 2.7, I
cannot stop the printer from printing the cover page. I accessed admintool and
deselected "Always print banner", I still have no success.
Thank you
Cindy
Answer : An
lpadmin [printer name and other options] -o nobanner
should stop the behavior. Use lpadmin and lpstat [-a] to get the name of the
printer to modify.
--
Paul Doherty
http://members.home.net/iqueue
FUQuestion : Hi
It still does not work. I accessed this site to install the software:
http://www.hp.com/cposupport/swindexes/hpjdprinte18924_swen.html#Solaris%207
Answer : Found the answer by going to that URL and clicking the "Solve a
problem" link, then put in "stop banner page".
http://www.hp.com/cposupport/networking/support_doc/bpj02755.html
--
Paul Doherty
http://members.home.net/iqueue
Rating : 5
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QAId : 4330224
Asker : jtaber
Subject : Magnetism
Private : No
Question : Why isn't manganese ferromagnetic when it actually has one more
unpaired electron than iron?
Answer : It has less to do with electrons being unpaired than it has to do with
the spins of elctrons failing to be cancelled out by the alternate spins of
neighboring electrons.
Cecil has the "Straight Dope" on this one:
http://www.straightdope.com/classics/a3_339.html
--
Paul Doherty
http://members.home.net/iqueue
Rating : 5
----------------------------------------------------------------------
QAId : 4413506
Asker : Anonymous
Subject : Ultra Volet light
Private : Yes
Question : Ultra Volet light carries vitiam D.
Is this true?
Someone told me and I just want to check if they lied to me again.
Thanks bye
Answer : That's not quite the way to say it. The ultravioler light doesn't
contain vitamin D - it causes your skin to *produce* vitamin D. Therefore small
quantities of sunshine can be beneficial.
--
Paul Doherty
http://members.home.net/iqueue
Rating : 5
----------------------------------------------------------------------
QAId : 4481137
Asker : Anonymous
Subject : Entrophy
Private : Yes
Question : Hi,
I read a good book entitled, "Hyperspace" by Michio Kaku. The author discusses
many topics ranging from wormholes, parallel dimesions, hyperspace, and the
eventual death of not just the earth itself but the universe as well. He
mentions that in about a billion years from now our atoms will eventually return
to the sun. Consider the following thought experiment:
Imagine that one scientist achieved immortality where all his cells are
constantly regenerating without limitations.
1)If he lived to be a billion years old, barring injury or illness, will all of
his atoms still turn to dust due to entrophy?
Dr. Kaku also stated that the universe will end in one of two possible ways:
a)It will contract and collaspe into a fiery ball
or
b)It will expand forever while all the stars in it's path will darken and end in
an ice age
He has no doubt that when the earth is destroy once our sun goes supernova,
humanity will take it's rightful place among the stars and collonize the galaxy.
The real threat is the death of the universe. He believes that humanity's only
salavation is to master the art of Hyperspace and entered it before the universe
takes our species to it's ultimate doom.
2)Has it been proven at least mathematically that it could exist?
3)Obviously it would take a whole lot of energy but could humans in 4 billion
years accomplish this?
regards,
Danny
Answer : As for question #1 - if we take your statement
"Imagine that one scientist achieved immortality where all his cells are
constantly regenerating without limitations."
and apply it to the question the answer would be no, he would not succumb to
entropy since he is already defeating entropy by our thought experiment
construct of him being immortal.
2. I have no knowledge of this "hyperspace" so I can't conjecture on its
existence or on question #3 which follows.
--
Paul Doherty
http://members.home.net/iqueue
DOS/Windows Utilities
Rating : 4
----------------------------------------------------------------------
QAId : 4520826
Asker : muddgrl34@...
Subject : MAth and skiing!?!
Private : No
Question : Hi i have a question for you. I am doing a project for my highschool
geometry class. I have to do a project on how math and skiing are related.
Mostly, do you know what the skies have to do with math and how the design of
the skies makes the skier go faster, turn better, or what not. Please get back
to me as soon as possible!!
THANK YOU!!
Answer : Well just off the top of my head there are a few areas of physics that
come to mind:
gravity (what makes you go down the hill ;-)
inertia (why it hurts to stop quickly)
rotational inertia (why shorter skis turn faster, and why longer skis have more
stability and speed)
regelation (see my previous answer on physics and hockey for full details -
http://www1.askme.com/SearchResults.asp?pm=va&AnswerRating=&cid=852&xShowNew=1&QA=on&xid=50373&query=hockey&prev=QA%2520&vid=1075481)
Let me know if you need something else on this...
--
Paul Doherty
http://members.home.net/iqueue
DOS/Windows Utilities
Rating : 5
----------------------------------------------------------------------
QAId : 4607472
Asker : jtaber
Subject : Liquid Oxygen
Private : No
Question : What is the surface tension of liquid oxygen and liquid nitrogen?
Answer : These are as close as I could get...
http://www.chipscalereview.com/9809/m.abtewb1.htm
http://members.spree.com/education/UVKChem/page2.htm
--
Paul Doherty
http://members.home.net/iqueue
DOS/Windows Utilities
Rating : 5
----------------------------------------------------------------------
QAId : 4613332
Asker : Anonymous
Subject : Watt's
Private : Yes
Question : How did they get the name watt's and how come watts is equal to V
times I? I mean how come I means amps?
Thanks bye
Answer : It's named after James Watt.
http://www.dictionary.com/cgi-bin/dict.pl?term=watt
As for using I for amps I have no clue. My best guess without doing any research
is that it was named after a similar concept from long ago.
--
Paul Doherty
http://members.home.net/iqueue
Home of DOS/Windows Utilities
Rating : 5
----------------------------------------------------------------------
QAId : 4652748
Asker : Anonymous
Subject : leverage
Private : No
Question : how do you figure leverage?
for example: if you have a pole extending from a base 3 feet with 1,300 hundred
pounds at the end how much pressure is at the base?
Answer : Diving the torque (turning pressure) is easy. Just take the distance
from the fulcrum (point of support) to the point of the application of force,
and multiply it by the force applied. To determine whether a certain weight
object on the other side of the fulcrum can be lifted use the same principle.
For example if the object on the other side weighs twice as much as the force
being applied on this side of the lever there will need to be twice the distance
to the fulcrum on the force-applied side to lift it.
--
Paul Doherty
http://members.home.net/iqueue
DOS/Windows Utilities
----------------------------------------------------------------------
QAId : 4673695
Asker : Anonymous
Subject : Science project
Private : No
Question : I measured water, soil and air heated by sunlight and found the soil
retained the highest temp over the 5 day period-why? also, the air came in
second for retaining heat-why?
thanks for any in put
Answer from FAQ : 2677367
specific heat capacity
8/28/2000
If by "retained the highest temp" you mean the highest average temperature over
the time you measured I would say that the soil was the highest since it's dark
in color and absorbed more light (less reflected). And water has a notoriously
high specific heat (resistance to change in temperature) so that would explain
why the air would be warmer than it.
See my FAQ I referenced below for my longer answer on specific heat of water
compared to other materials.
--
Paul Doherty
http://members.home.net/iqueue
Home of DOS/Windows Utilities
----------------------------------------------------------------------
QAId : 4675627
Asker : kinkyangel666@...
Subject : physics of bungee barbie
Private : Yes
Question : In physics we have a lab assignment, and the assignment is to figure
out a way to get a barbie really close to the ground, but the barbie cannot
touch the ground, to do this we have to create our own bungee cord, what i dont
understand though, is how does this relate to physics?....the only solution i
see, is trial and error.
Thankyou for your time and consideration
Sincerely
Angel
Answer : Nothing says physics means you predict the answer before the
experiment. Sometimes if you don't know enough about the factors involved you
may have to perform some runs to learn what is significant so you can then make
predictions based on that info.
Seems to me suspecnding Bungee Barbie(TM) from rubber bands on each hand and
tying a weight to her feet would have a good chance of accomplishing what you're
after.
Let me know if you need something else.
--
Paul Doherty
http://members.home.net/iqueue
Home of DOS/Windows Utilities
----------------------------------------------------------------------
QAId : 4714371
Asker : Anonymous
Subject : pictures of a Fluorine atom
Private : No
Question : Where can I find pictures of a Fluorine atom to help me make a model?
I need answers fast!
Answer : http://www.google.com/search?q=images+flourine+atom
--
Paul Doherty
http://members.home.net/iqueue
Home of DOS/Windows Utilities
----------------------------------------------------------------------
QAId : 4723144
Asker : jon1149
Subject : rockets
Private : No
Question : I don't understand why rockets and space shuttles don't just topple
over when taking off. Surely a slight gust of wind or a slight inbalance in the
upward thrust would cause them to fall over! Can you explain this?!
Thanks
Answer : For low speeds this is probably true. Once the rockets gets moving the
shape of it acts like a dart in thw wind, providing little resistance at the
front and a lot at the rear (which serves to keep the back, well, in back :-)
--
Paul Doherty
http://members.home.net/iqueue
Home of DOS/Windows Utilities
Rating : 5
----------------------------------------------------------------------
QAId : 4747923
Asker : mgindorff
Subject : acceleration due to gravity.
Private : No
Question : How far will a 20 kg rock in 5 seconds? We are
in disagreement about the answer.
Solution 1: Using 9.8 m/sec/sec= (V final- O m/sec) / 5
We came up with 49 m/sec.
Using the formula for speed we went 49 m/sec times 5 sec
and came up with a distance of 245 meters.
Solution 2: If you manually add the acceleration of gravity
You come up with 156.8 meters.
Which is correct and why?
Answer : I get 122.5 meters of fall after 5 seconds. I think you made a slight
mistake when you got 49m/sec and then multiplied *it* by 5 seconds. The thing to
remember that 9.8m/sec is the amount of speed *added* over each second of fall.
For example if you drop a rock and let it fall one second *at the end of that
second* it will be travelling at a rate of 9.8m/sec, but it won't have travelled
that far. Why is that? Because at the beginning of the second it was holding
perfectly still, and at the end it was travelling at 9.8m/sec with smooth
acceleration all in between. So you must find it's *average* speed over that
second by dividing the time in half (we're multiplying by 1/2 (.5) but it's the
same thing). The formula for the distance fallen when you know the time the
object has fallen is:
1/2gt^2
where g is 9.8m/sec for gravity
t is time in seconds for the fall
So when we plug in your numbers:
1/2 * (9.8 * 5^2)
1/2 * (9.8 * 25)
1/2 * (245)
= 122.5m of fall after 5 seconds.
If you want to know how fast the object is falling at the end of any particular
second just multiply the gravitational acceleration by the number of seconds of
fall:
5 seconds of fall:
gt
9.8 * 5 = 47.5m/sec at the end of 5 seconds
For more info see one of my questions I previously answered on a tennis shot
that deals with gravitational fall:
http://www1.askme.com/MyXpertise.asp?pm=va&method=faq&cid=852&viewfaq=1&page=1&vid=3239956
--
Paul Doherty
http://members.home.net/iqueue
DOS/Windows Utilities
----------------------------------------------------------------------
QAId : 4776025
Asker : brl
Subject : waves
Private : No
Question : Only xrays and gamma are shorter than________ waves?
Answer : Ultraviolet fits there, but there may be some shorter than UV but
longer than gamma and x-rays.
--
Paul Doherty
http://members.home.net/iqueue
DOS/Windows Utilities
Rating : 5
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QAId : 4780528
Asker : JTP22
Subject : speed of light
Private : No
Question : im a year 12 physics student and recently asked my teacher a question
that he could not answer.
here it is:
if two people were BOTH traveling at the speed of light (i know that thier mass
becomes infinte but just suppose)and they look at each other what would they
see?
becase of properties of light (V is always constant)i dont know that answer!
would they see eachother as still?
please answer in detail.
also can you prove it?
can you give me any sites too?
Answer : This is part of how Einstein came up with the theories of relativity
(general and special). He imagined what the world would look like if travelled
alongside a beam of light. That conundrum nearly drove him mad but in the end it
led to relativity.
Cecil Adams has a fine answer that directly relates to your question - the
answer being that both observers do not know they are moving (they are in the
same frame of reference) and therefore share the same time frame (they age at
the same rate).
http://www.straightdope.com/classics/a3_143.html
--
Paul Doherty
http://members.home.net/iqueue
DOS/Windows Utilities
----------------------------------------------------------------------
QAId : 4786060
Asker : sarah_luvs_ya
Subject : highschool physics
Private : No
Question : If one were to roll a steel, a glass, a rubber, and a wood ball down
a wooden piece of molding and the balls were approximately the same size but had
different masses I thought that the heavier the ball the faster it would go down
the ramp. When I tried it didn't work out this way. Were the balls supposed to
all go at the same speed? Would the coefficient of friction, gravity, or air
resistance have anything to do with it? momentum? anyhting else??
Thanx
Answer : If the balls were all the same size they should roll very close to the
same speed. A ramp experiment like this is merely simualting a slow-motion
freefall, as if you had dropped these same balls off a building. I believe it
was Galileo who first did these ramp experiments and he reasoned as above that
the inclined plane (neglecting frictional forces) did not change the base
concept that the balls accelerate due to gravity. And if the balls are slowed by
the ramp (of course they arem in relation to how fast they would go falling
unhindered) they are all slowed by the same amount. This decrease in
acceleration for these "falling" objects made gravity easier for Galileo to
study. The diameter of the ball can affect the speed, as can the composition of
the ball. Air resistance will have nothing to do with it unless you have a long
ramp to get the balls up to appreciable speed. Then air resistance is a function
of surface area (all the same) and weight (different since made of different
materials). Each ball will end up with a different amount of momentum, since
momentum is made up of velocity and mass (and each ball's makeup is different -
some materials being more massive than others).
--
Paul Doherty
http://members.home.net/iqueue
Home of DOS/Windows Utilities
Rating : 5
----------------------------------------------------------------------
QAId : 4882276
Asker : Anonymous
Subject : Sound waves traveling
Private : No
Question : Dear Paul,
I do not have a background in physics.
My questions:
If sound waves travel, where do they go?
Would it be possible to retrieve (recall) them?
I know that these probably sound like stupid questions, but my father and I were
having a discussion about this and he doesn't think that such a thing is
'far-fetched.' He feels that maybe someday scientists will be able to hear
Moses's sermon on the mountain, for example.
Thank you.
Answer : I'm going to have to say that's unlikely (recovering speeches that were
uttered any time ago). The reason is that sound is merely a temporary
disturbance of a medium. For example when you strike a tuning fork it visibly
oscillates and produces a sound. When the vibration finishes and no more sound
is being generated both fork, and the air that transmitted the sound to your
ears, is back in a quiescent state. No evidence of the sound will remain in the
fork or the air (or your ears for that matter). The only place the sound may
reside is in your memory or a recording device. Absent either of those (a
listener still alive, or a recording device) it's not possible to retrieve sound
that I'm aware.
--
Paul Doherty
http://members.home.net/iqueue
DOS/Windows Utilities
Rating : 5
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QAId : 4952631
Asker : esbee123
Subject : physics
Private : No
Question : why is a turboprop engine of an aircraft affected by speed of sound
whereas turbojet aircrafts fly more than the speed of sound.
Answer : Here's a discussion on the subject - apparently there is nothing that
would prohibit it, but the propeller-based engine produces a horrible amount of
sound:
http://groups.google.com/groups?q=turboprop+speed+sound&hl=en&lr=&safe=off&rnum=4&seld=995901438&ic=1
--
Paul Doherty
http://members.home.net/iqueue
Home of DOS/Windows Utilities
----------------------------------------------------------------------
QAId : 4991601
Asker : RobertHeller
Subject : Gravirt assisted acceleration of spacecfaft
Private : Yes
Question : I am working on a SF novel and want to have some level of reality in
it. The novel involves a Busard Interstellar Ramjet. I want to be sure I have
things working realistly. I am having the spacecraft launched from the Moon
(magnetic levitation railroad launcher), into a close solar orbit (about the
orbit of Mercury. I understand that a Busard Interstellar Ramjet needs to get up
to about .04c to be going fast enough to collect enough protons to fire up its
fusion engine. I have written a C program to calculate the rate of acceleration
needed to achive this speed by about the orbit of Mercury, but I am not getting
'sane' numbers. I suspect that my math is totally wrong.
I need to know for my book:
1) How much acceration the magnetic levitation railroad launcher needs to impart
on the ramjet.
2) How much additional acceration the sun's gravity will add.
3) How long it will take to 'fall into the sun'.
4) How much acceration would be reasonable to maintain once the ramjet has gone
around the sun and begins heading out into interstellar space and how long will
it take to get as far as the Oort cloud and how fast it will be going by then.
Thanks in advance for any help.
Answer : I would expect there is only one "right" speed at which to launch the
vehicle and still arrive for orbital capture at the desired distance from the
Sun. Once you fall into orbit with the Sun there will be an increase in velocity
due to the "gravity whip" as I like to call it - this gravity whip is precisely
why I believe there is only one correct speed to approach. Approach too slow and
the gravity whip will accelerate you right into the Sun quickly - approach too
fast and the gravity whip sends you flying away from the Sun at higher speed.
That may make a good device for you - have the maglev rocket the ship off the
moon at high speed, with a trajectory calculated to "skim" the Sun for an
additional boost of acceleration which brings it to the necessary speed to kick
in the ramjet. Or you could stick with a "decaying orbit" idea, where once the
ship has entered a decaying orbit around the Sun, it's velocity (and temp! makes
for some more drama as the heat rises) continues to increase to the speed
necessary to start the ramjet and escape.
Once you're off at whatever final speed you're moving at just divide the
distance to the Oort cloud (30 trillion kilometers) by that speed to get the
time needed for the trip.
Best of luck on the book,
Paul Doherty
http://members.home.net/iqueue
Home of DOS/Windows Utilities
FUQuestion : I understand about the 'gravity whip' idea. I just need some help
calculating the amount of acceration the maglev needs to impart and how much
additional acceration will be gained by the sun's gravity and how much
acceration the ramjet can maintain to achive solar escape velocity.
Declined (Reason) : Can only help on the concept, not the fake math - Contact
NASA for that... :-)
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QAId : 4993541
Asker : cyberpal_1@...
Subject : physics
Private : No
Question : dear expert,
iam a layman in physics, out of touch with it since school.
but iam interested in knowing about Albert Einstein's formula e=mc^2 . what do
the alphabets stand for in the formula and what does it explain?
regards ,
Cyberpal.
------------------------------------------------
Answer : In the formula:
e - the total energy contained in the mass of an object
m - the "rest mass" of the object
c - velocity of light
What it says: The amount of energy in a physical object is equal to the mass of
the object times the velocity of light squared.
In a nutshell what the forumula means is that energy and mass are one and the
same thing. All objects are simply congealed energy, and energy contains mass.
It is a "mass-equivalence" formula. If you need further information regarding
this let me know.
--
Paul Doherty
http://members.home.net/iqueue
Home of DOS/Windows Utilities
Rating : 5
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QAId : 5002266
Asker : yakkuli
Subject : how a microwave oven works
Private : No
Question : how does a microwave oven cook without any ignition or fire etc.?
Answer : Instead of a normal oven where heat is moved via conduction and
convection a microwave oven works off the principle of "forced resonance". The
wavelength of radio waves ("microwaves") used in a microwave oven happen to
produce atomic resonaces (vibrational motion) in water and fat molecules. These
motions are heat and are then conducted throughout the material. See this
article for more details:
http://www.howstuffworks.com/microwave.htm
--
Paul Doherty
http://members.home.net/iqueue
DOS/Windows Utilities
Rating : 4
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QAId : 5002282
Asker : Anonymous
Subject : rain
Private : No
Question : does one get wetter running or walking in the rain? This is assuming
that one has no umbrella.
Answer : There is no difference (amazingly I too have pondered the question!
hehe). If you think about it this way running only changes *where* you get wet.
By running you are catching up to raindrops in front of you (that subsequently
hit your front and legs) that would normally have fallen in front of you. So by
running you may find yourself soaked in front but relatively dry in the back.
You can't win for losing huh?? :-)
--
Paul Doherty
http://members.home.net/iqueue
DOS/Windows Utilities
Rating : 5
FUQuestion : Thanks...it would make sense then that if you run, you're spending
less time so you get less wet. (I ask b/c this is a bet)
Answer : Well let's compare two situations:
1) Standing perfectly still in the rain
2) Running at full sprint in the rain
In situation #1 (we're assuming that the rain is falling perfectly vertical for
this discussion) you'll note that there isn't much surface area you're exposing
to the rain - mostly just your head and shoulders (unless you've been partaking
of the pasta a bit too much! ;-)
In situation #2 you are now exposing your head and shoulds *AND* almost your
entire frontal area to raindrops, which would result in you getting at least as
wet if not more wet than in situation #1 (perhaps only equal due to the lesser
time during which you are exposed to the rain since you're running).
So I would still call it a draw. You guys keep your money and shake hands. :-)
--
Paul Doherty
http://members.home.net/iqueue
DOS/Windows Utilities
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QAId : 5002300
Asker : sosoboy41
Subject : measuring volume
Private : No
Question : what are the different methods of measuring volume?
Answer : I don't know about multiple ways. The best way I know of to get the
volume of an irregular-shaped object:
1) Fill a container larger than the object completely full of water.
2) Place a larger container below that one to catch the water.
3) Attach the object to be measure to a string (or if it's a bouyant object to a
stick) and submerge the object completely in the top tub. This will displace
water into the tub below. Submerge it slowly so no spills or extra "waves" are
produced.
4) Now measure the volume of water captured in the tub below. That volume is the
same as the object you submerged.
--
Paul Doherty
http://members.home.net/iqueue
DOS/Windows Utilities
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QAId : 5002317
Asker : jtucker81
Subject : momentum2
Private : No
Question : You are standing on a log and a friend is trying to knock you off. He
throws the ball at you. You can catch it, or you can let it bounce off of you.
Which is more likely to topple you, catching the ball or letting it bounce off?
Please explain your answer in some detail
Answer : You are more likely to be toppled if you let it bounce off of you. If
you catch it the only momentum inparted is the initial momentum from the other
person's throw (the ball coming to rest with you). If instead you let it hit you
and bounce away you will have absorbed the initial momentum *plus* given it new
momentum in the opposite direction, which means that you will experience a force
equal to that negative momentum in the backwards direction.
The same concept is used with rubber bullets for crowd control. They don't get
absorbed like a lead bullet does so they don't usually cause any great harm, but
they pack a knock-down wallop since they rebound off the victim.
--
Paul Doherty
http://members.home.net/iqueue
DOS/Windows Utilities
Rating : 5
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QAId : 5002321
Asker : sosoboy41
Subject : how to measure volume?
Private : No
Question : how can i measure volume
Answer : The best way I know of to get the volume of an irregular-shaped object:
1) Fill a container larger than the object completely full of water.
2) Place a larger container below that one to catch the water.
3) Attach the object to be measure to a string (or if it's a bouyant object to a
stick) and submerge the object completely in the top tub. This will displace
water into the tub below. Submerge it slowly so no spills or extra "waves" are
produced.
4) Now measure the volume of water captured in the tub below. That volume is the
same as the object you submerged.
--
Paul Doherty
http://members.home.net/iqueue
DOS/Windows Utilities
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QAId : 5002365
Asker : starshine1729
Subject : Terminal Velocity
Private : No
Question : A free falling body may experience terminal velocity. Please explain
terminal velocity in terms of a free falling body. Thank You!
Answer : Terminal velocity is simply the maximum unassisted speed that an object
can fall in air. Two aspects of an object contribute to what this speed will be
- it's mass (weight) and it's surface area (amount of the object exposed to
air). What happens is as the speed of the fall increases so does the effect of
the air your strike as you fly downwards. If you continue to accelerate long
enough (like in a sky dive from altitude) evetually you will stop accelerating
when the force of the air resistance you enounter equals your weight.
Human beings are large and thus tend to have a large volume relative to our
surface area. So our terminal velocity is quite high - around 125 MPH. An ant or
a feather have very little volume and tons of surface area (think of the tiny
wisps that make up a feather, or the skinny legs of an ant) so their weight will
be equalled at a far lower speed. The terminal velocity of an ant is likely
around 3 feet per second. That's why you can drop an ant from the ceiling and
he'll walk away. So that to a human and they'll be lucky to not be heading to
the hospital with an injury!
--
Paul Doherty
http://members.home.net/iqueue
DOS/Windows Utilities
Rating : 5
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QAId : 5002411
Asker : starshine1729
Subject : Satellite Orbit
Private : No
Question : Please explane how satellites orbit the earth. Why do they continue
to orbit and not fall to earth? Why do they stay in orbit and no "run off" into
space? Thank You!
Answer : A satellite *does* fall towards Earth. The gravitational force at that
distance is greatly diminished but it's still quite present. The Earth curves in
a fairly uniform fashion - every X distance travelled horizontally equates to Y
drop in altitude. At ground-level it's about 4.9 meters of drop for every 8
kilometers of lateral distance. In space the distances are greater but the
concept is the same. For the satellite to experience the same rate of fall (and
maintain its distance from the Earth) it needs to travel a horizontal distance
during each second of fall that will bring it to the same height above the
ground as it was at the beginning of the second. So in essense the satellite
"falls around the Earth" rather than into it. If the satellite's speed begins to
slow it will be what is called a "decaying orbit" where it is no longer
travelling the lateral distance required each second, so therefore it is now is
a "spiral" of sorts, losing altitude with each second. If it goes faster than is
needed to maintain the orbit it will gradually gain altitude and eventually
launch out into space.
--
Paul Doherty
http://members.home.net/iqueue
DOS/Windows Utilities
Rating : 3.5
Rating : 3.5
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QAId : 5002426
Asker : Anonymous
Subject : The movement of the water
Private : No
Question : When I fill up a sink with water and let water go, the whirlpool
turns clockwise. I know that this also occurs in the south-hemisphere
oppositely, I would like to know what direction of the whirlpool would turn when
we are in the exact North Pole or the equator.
Answer : Flip a coin and find out. Unless the water is *completely stable and
non-moving* (very rare) it will have an equal chance of developing a spin in
either direction.
--
Paul Doherty
http://members.home.net/iqueue
DOS/Windows Utilities
Rating : 3
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QAId : 5002476
Asker : wto2k
Subject : why sky is blue
Private : No
Question : How come sky is blue ?
Thanks for your time !!!
Answer : The sun produces light of almost all frequencies (white light). When
that light attempts to penetrate our atmosphere some of the frequencies interact
more than others. Particularly the higher frequencies of blue and ultraviolet
(just above our range of perception). They set off sympathetic virations in the
atomic structures of the various molecules that make up our air and these atoms
in turn release photons of light in the same frequency range. Much like a bunch
of tuning forks setting each other off. This scattering effect is what colors
the sky blue, as those atoms respond to the frequencies closest to their own.
Interstingly, if you could see ultraviolet light with your eyes you would find
that the sky is actually ultraviolet in color, not blue since ultraviolet has
the highest resonance with the air molecules.
--
Paul Doherty
http://members.home.net/iqueue
DOS/Windows Utilities
Rating : 4
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QAId : 5024883
Asker : bandhani
Subject : heat
Private : No
Question : 1)Why burning by steam is severe than hot water while both attain
same temperature ?
2)what is the difference between latent heat and specific heat ?
Answer : 1) A steam burn is worse because it contains the extra energy that
brought the water from a liquid to a vapor state (and a vapor state is more
"energetic" than liquid of the same temp) - specifically 540 calories per cubic
milliliter more, if memory serves me.
2) http://www.sasked.gov.sk.ca/docs/midlsci/wwwboard/messages/3845.html
--
Paul Doherty
http://members.home.net/iqueue
DOS/Windows Utilities
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QAId : 5144382
Asker : Anonymous
Subject : INSULATING PROPERTIES OF VARIOUS MATERIALS
Private : Yes
Question : My 5th grader is doing a sci fair project. He's testing 5 different
cups (clear glass, foam, paper, plastic, stoneware)to see which will keep water
hottest over a 20-min. period. He must write an accompanying research paper.
Where can he find info on the insulating capabilities of these various
materials? He's also stuck on what the control should be. Any help or advice
would be much appreciated.
Answer : In my opinion no resources on the insulating proerties is required as
that is the point of his research. He will be discovering their properties and
that is the point of the experiment.
I would suggest that he have the 5 cups being tested (identical size and shape
and amount of water in each, poured from the same kettle so the water is
identical in temp). As for the control I would look for a *metal* cup (like a
metal measuring cup), as it has no insulating properties to speak of, and will
bleed off heat at the highest expected rate. All the other cups should retain at
least as much if not more heat than the metal cup and so the metal cup will
serve well as a compariso