# Relativity physics homework problem

1. Aug 21, 2008

### matt14690

A 1000m long and 200m wide (when at rest) spaceship equipped with a chronometer is sent on a roundtrip
to their Galactic Base, 8 light years away.
(a) Astronauts start the trip after celebrating their captains 29th birthday and they want to make a round
trip and return to Earth on the eve of the captains 30th birthday. The ship travels with a constant velocity.
Calculate the required speed of the spaceship.
(b) According to the clocks on Earth, how long does this trip take?

Need help with the process to follow for (a)

2. Aug 21, 2008

### HallsofIvy

Re: Relativity

Use the Lorentz tranformation formula for time to determine, in terms of the velocity relative to earth, v, how much "earth time" will be required if the trip to one year in "ship's time". Set that equal to 8 lightyears/v and solve the equation for v.

3. Aug 21, 2008

### Varnick

Re: Relativity

You'll want to look at relativistic time dilation, according to the Lorentz factor. Once you've looked at this, have a go at a calculation.

EDIT: What HallsofIvy said.

V