Since this thread was moved from the Advanced to Introductory section, I thought it would be appropriate to bump, hopefully someone can offer a hint for me to continue. Thanks in advance.
Homework Statement
A Spaceship is moving with speed ß=4/5.
Its length at rest is 1sec. A light is turned on at the rear of the ship, reflected back from a mirror at the front.
a.) How long does an observer at rest say it takes for the light to return to the rear of the ship (total round...