College Physics 10th Edition by Raymond Serway,Chris Vuille

Exercise 55

If astronauts could travel at v = 0.950 c , we on Earth would say it takes (4.20/0.950) = 4.42 years to reach Alpha Centauri, 4.20 light-years away. The astronauts disagree. (a) How much time passes on the astronauts' clocks (b) What is the distance to Alpha Centauri as measured by the astronauts