Special Relativity - Help!

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1. Oct 5, 2014

elevenb

1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution
Hey, I would really appreciate some help with this. I have worked out the Lorentz factor to be 5.025. Am I right to assume that Δx = 200000km, and Δt' = 1.2s and I have to work out Δt and Δx'?

If these are correct I have worked out Δt to be 0.8926 and Δx' to be -3.12(*10^8)? It doesn't seem right..

2. Oct 5, 2014

Simon Bridge

$\gamma=5.025$ yes.
You have not defined your variables or explained your method so I cannot tell what you hoped to find.

Take a step back and consider - the observer is A, the planets are E and G (saves typing).
A,E,G are in a line ... A saw the flash from E first and from G second ... what is the sequence of events?
Can you construct the timeline in A's reference frame?

3. Oct 5, 2014

elevenb

The line is A,G,E no? Well if I go purely by intuition, I would assume that in A's reference frame E fired first, and then G fired in reply. Which would make sense at non relativistic speeds. I just am not sure how I bring the speed of A into it to find out who fired first in E and G's frame of reference. (Which is what I am looking for?)

4. Oct 6, 2014