| Topic: |
Science > Physics |
| User: |
"" |
| Date: |
20 May 2006 10:32:17 PM |
| Object: |
Theoretical experiment on relativity |
Consider a train , its proper length = 375000 km , traveling at a speed
of 180000 km/sec (0.6 of speed of light) relative to person (name him
B)
Consider a beam of light that travels in the same direction of the
train
The train traveler (name him A) will measure the train length = 375000
km , & will measure time required for light beam to travel from the
back of the train to the front of the train = 1.25 second (as light
travels in a speed of 300000 km/second)
B will measure the length of the train = 300000 km (as length
contraction occurs) , & will measure time required for light beam to
travel from the back of the train to the front of the train = 1.5625
second (as time dilation occurs for time of A)
B will measure the distance that light beam traveled = 180000 * 1.5625
(the distance that train traveled) + 300000 (the length of train as B
measured it) = 281250 + 300000 = 581250 km (B will measure that light
travels this distance at 1.5625 second) i.e. B will measure the speed
of light = 372000 km/second
Does this prove that light speed is not constant for all observers?
Thanks
.
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| User: "The Ghost In The Machine" |
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| Title: Re: Theoretical experiment on relativity |
21 May 2006 11:00:07 AM |
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On Sat, 20 May 2006 20:32:17 -0700, wrote:
Consider a train , its proper length = 375000 km , traveling at a speed
of 180000 km/sec (0.6 of speed of light) relative to person (name him
B)
Consider a beam of light that travels in the same direction of the
train
The train traveler (name him A) will measure the train length = 375000
km , & will measure time required for light beam to travel from the
back of the train to the front of the train = 1.25 second (as light
travels in a speed of 300000 km/second)
B will measure the length of the train = 300000 km (as length
contraction occurs) , & will measure time required for light beam to
travel from the back of the train to the front of the train = 1.5625
second (as time dilation occurs for time of A)
B will measure the distance that light beam traveled = 180000 * 1.5625
(the distance that train traveled) + 300000 (the length of train as B
measured it) = 281250 + 300000 = 581250 km (B will measure that light
travels this distance at 1.5625 second) i.e. B will measure the speed
of light = 372000 km/second
Does this prove that light speed is not constant for all observers?
Thanks
"Thought exercises" prove nothing, though they might illuminate
understanding. In any event B will "measure" the length of the train
using a light beam or radar unit using the formula
sqrt(1+v/c)/sqrt(1-v/c), not 1/sqrt(1-v^2/c^2), because the two endpoints
of the train are an different times during the measurement.
That gives B a length of 187500 km, and a time of 0.625 s.
As the train flashes by him B can repeat the experiment, and then gets a
length of 750000 km and a time of 1.25 s.
--
#191,
It's still legal to go .sigless.
.
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