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Relativity: Spaceship travel times and distances

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1. Homework Statement
A star is 95.0 year lights away from Earth. How much time does it take to a cosmic ship, which moves with speed 0.96 c, to reach the star, if it is measured from a watcher from a) Earth a)ship c)What si the distance of trip, based on the viewer from the ship?

2. Homework Equations
t=L/v
Lr=L*sqrt(1-v^2/c^2)

3. The Attempt at a Solution
a) t=L/v=99 years
c) Lr=L*sqrt(1-v^2/c^2)=26.6 years
b) tr=Lr/v=27.7 years.
I'm not sure if for this I should use tr=t/sqrt(1-v^2/c^2). Which one is the best to use because the results are different. But if I use tr=t*sqrt(1-v^2/c^2) it has the exact same result. If 27.7 years is the correct answer, then why should the length contract and time not dilate?
 
Last edited:

BvU

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Is your problem description complete ?
In part a) , what do you use for L and what do you use for v to get 99 y ?
 
56
1
Is your problem description complete ?
In part a) , what do you use for L and what do you use for v to get 99 y ?
I had forgotten to put the speed. it is 0.96 c
 

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