Special relativity of a light source moving downstream

AI Thread Summary
The discussion revolves around calculating the speed of light signals emitted from a light source moving downstream in water flowing at speed v. The first point of inquiry is determining the downstream speed of light signals, while the second focuses on the upstream speed. A critical consideration is the behavior of the upstream signal when the water speed v is less than the speed of light in water (cw). Participants are encouraged to apply relativistic velocity addition principles to solve the problem, noting the lack of time data complicates the calculations. Understanding these concepts is essential for accurately addressing the homework questions.
matt_crouch
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Homework Statement



Let Cw be the speed of light through water at rest. Water is now flowing at speed v parallel to the x-axis according to one observer, and there is also a light source moving with the water at speed v

1) what is the speed at which the light source sends light signals in the downstream direction?
2) what is the speed at which the light source sends light signals in the upstream direction
3) What happens for the upstream light signal, if v<cw?

a. the signal propagates in the positive x direction
b.the signal propagates in the negative x direction
c the signal propagates at zero speed


Homework Equations





The Attempt at a Solution



i don't really know where to start. I was going to use the equation

x=(gamma)(x'-vt')
but since we don't have the time
im not really sure thanks in advance
 
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Hint: How do velocities add relativistically?
 

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