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## Homework Statement

An astronaut travels from the earth at a speed of 0.999c to a star that us 15 light-years away (as measured by someone from earth). she spends 10 years on one of the star's planets (as measured by someone on that planet) and then returns to earth at 0.999c. How long has she been away (1) as measured by someone on the earth and (2) as measured by her?

## Homework Equations

Δt = γ Δt'

## The Attempt at a Solution

I am trying to measure the time it took for her to go to the planet and come back by

Δt = γ(1+(1/2)* β^2 )

and then the time she spent on the planet counted by someone on the earth by

Δt = γ Δt'

where ............Δt' = 10 yr ........is this right

and add all the values ....

For the B part I calculated the distance for her in the ship

by L = Lp √ 1- β*β

and based on this new distance did the same calculation as part A ....