AP French Relativity chapter 3 problem

In summary, the conversation discusses the use of the relativistic Doppler shift in finding an answer to a problem, but one participant suggests that it may not be applicable due to the dependence of the speed of light on the motion of the source. The conversation then provides two questions to consider, including the function for expressing velocity and the time at which light was emitted from the star based on certain assumptions.
  • #1
ka_reem13
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0
Homework Statement
the question is contained in my attempt at a solution as I can't add images anywhere else
Relevant Equations
I assume we will have to use the relativistic doppler shift in order to find our answer, but that's all I can really gather from how to attempt this
Screenshot 2023-02-03 at 06.56.49.png
 
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  • #2
ka_reem13 said:
Relevant Equations:: I assume we will have to use the relativistic doppler shift in order to find our answer, but that's all I can really gather from how to attempt this
I think French wants you to assume that the speed of light depends on the motion of the source. In which case, you cannot use the relativistic Doppler shift, but have to calculate the shift for yourself.
 
  • #3
ka_reem13 said:
Relevant Equations:: I assume we will have to use the relativistic doppler shift in order to find our answer, but that's all I can really gather from how to attempt this

This problem does not require any results from relativity. The star's speed is much less than the speed of light. Consider the following:

(1) What is the function ##v_r(t)## that expresses ##v_r## as a function of time ##t## and the orbital period ##T##? For convenience, choose ##t = 0## when the star is farthest from the earth.

(2) Suppose someone on earth at an arbitrary time ##t## observes light from the star. At what earlier time ##t_0## was this light emitted from the star under the assumption that the light travels from the star to earth at speed ##c+v_r(t_0)##? Express ##t_0## in terms of ##t##, ##R##, ##c##, and ##v_r(t_0)##.
 

FAQ: AP French Relativity chapter 3 problem

What is the main concept covered in Chapter 3 of AP French Relativity?

Chapter 3 of AP French Relativity primarily focuses on the principles of special relativity, including time dilation, length contraction, and the Lorentz transformations. It delves into the implications of these concepts for objects moving at speeds close to the speed of light.

How do you derive the Lorentz transformation equations?

The Lorentz transformation equations are derived by ensuring that the speed of light remains constant in all inertial frames of reference. This involves using the postulates of special relativity and algebraically manipulating the space and time coordinates of events in different inertial frames. The transformations account for the effects of time dilation and length contraction.

What is time dilation and how is it explained in Chapter 3?

Time dilation is the phenomenon where time appears to pass more slowly for an observer in motion relative to a stationary observer. Chapter 3 explains this using the Lorentz transformation equations, showing that the time interval between two events is longer (dilated) when measured in a reference frame moving relative to the events.

Can you explain the concept of length contraction?

Length contraction is the phenomenon where the length of an object moving at relativistic speeds appears shorter along the direction of motion to a stationary observer. Chapter 3 explains this by showing how the Lorentz transformations affect spatial coordinates, leading to a contracted length in the frame of reference moving relative to the object.

How does Chapter 3 address the concept of simultaneity in relativity?

Chapter 3 addresses the concept of simultaneity by demonstrating that events that are simultaneous in one frame of reference may not be simultaneous in another frame moving relative to the first. This is a direct consequence of the Lorentz transformations and highlights the relative nature of time in special relativity.

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