# Homework Help: Special relativity homework question time dilation

1. Nov 14, 2011

### natxio

1. The problem statement, all variables and given/known data
You are a passenger on a brand-new spaceship that travels at 95% of the speed of light, i.e.,
v = 0.95 × c. The spaceship is bound for the star, Altair, at a distance of 17 light years from
Earth. If the spaceship departs on your 21st birthday, at a speed of v = 0.95c, how old are you
when the spaceship arrives at Altair?

2. Relevant equations
Δtmoving = Δtrest x [square root of (1−v^2/c^2)]

v= d/t

3. The attempt at a solution
I have no idea how to do this problem, in my opinion it appears to be poorly worded, I don't know if the professor means age relative to earth time or age relative to the traveling speed. This is my attempt to find a solution:

v=d/t v=0.95c --> 0.95c= 17lightyears/ t

t= d/ v

t= 17ly/ 0.95 c

Last edited: Nov 14, 2011
2. Nov 14, 2011

### Delphi51

I sympathize with you; relativity really confused me, too! Even those guys at CERN measuring neutrinos were confused. I remember just enough to know that this question is very well worded - no nonsense about accelerating at the beginning or end to worry about. Just the Earth frame of reference. I think your calc is correct, but you better check here to be sure:
http://physics.bu.edu/py106/notes/Relativity.html

3. Nov 14, 2011