00:01
In this problem, we're going to talk both about transformation of velocity and length contraction.
00:05
So first, on transformation of velocity, consider that we have two reference frames.
00:10
In the first reference frame, as we have an object that's moving with the speed v.
00:20
I consider that in the second reference frame, s prime, the first reference frame is moving with the speed capital v in the same direction as the first object.
00:32
So what is the same? speed v prime that will be measured by the s prime reference frame.
00:41
Spectral activity tells us that v prime is equal to v plus capital v divided by 1 plus v capital v divided by c squared.
00:56
Also on length contraction, suppose that we have an object that has a proper length l.
01:04
This means that this is the length measured in the reference frame where the object is at rest.
01:10
And assume that this object is moving with a speed v relative to reference frame s, what an observer that's at rest relative to the s reference frame will measure for the length of this object is the proper length, divided by gamma, where gamma is 1 over the square root of 1 minus v squared over c squared.
01:39
Okay...