Special Relativity - Help Please!

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Homework Statement


Two twins start their clocks at the same time, one of them travels for 7 years at a speed of 4/5c, reverses direction and returns at half the speed. The other twin remains stationary, what is the difference in their age?


Homework Equations


t = t_p γ


The Attempt at a Solution



I'm hung up on the thought... when he reverses direction he travels at half speed. Intuitively I think that it takes him 14 years to return at half speed... but is this necessarily the case? How can I prove that it is necessarily 14 years for him to return (considering Lorentz contraction) or find the actual time it would take him to return?
 

Answers and Replies

  • #2
vela
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14 years as measured by whom? Same question for the initial 7 years.
 
  • #3
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The 7 years is as measured by the traveling twin's frame. So my intuition wants to say that his return is 14 years in his frame. However I think that this may be flawed due to lorentz contraction of the distance being traveled.
 
  • #4
vela
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Yes, you're right. It'll be longer than 14 years in that case. Not only is he going half the speed, he's having to travel a longer distance.
 

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