 #1
 32
 3
 Homework Statement:

Consider a source of light (for example, a star) and a receiver (an astronomer) approaching one another with a relative velocity v. First we consider the
receiver fixed (Figure 2.27a) in system K and the light source in system K moving toward the receiver with velocity v. The source emits n waves during the time
interval T. Because the speed of light is always c and the source is moving with
velocity v, the total distance between the front and rear of the wave train emitted
during the time interval T is
 Relevant Equations:
 Length of wave train = cT  vT
I am confused about how to find the length of a wave train emitted within a time interval T and that is moving with speed c relative to a moving frame that is itself moving with velocity v. Apparently the answer is that the wave train's length is cT  vT, but I tried to plug in variables into the Lorentz velocity transformation equation in the x direction and didn't get the right answer. I also tried to use the time dilation and length contraction equations but to no avail. Please see attachment for the figure.
Also, I am unsure whether the textbook is trying to find the proper length or is trying to find the length with respect to the stationary frame.
Also, I am unsure whether the textbook is trying to find the proper length or is trying to find the length with respect to the stationary frame.
Attachments
Last edited: