Alpha Centauri is not only the closest star system to us (it is actually a triple star system)but it also seems to be an excellent place to look for extra-terrestrial life.It is about 4.3 light-years away from Earth.If an astronaut claims her journey there and back only took 6.3 years,then how fast was she traveling? (Assume she made a fast turnaround once she arrived there!)
A)0.65c
B)0.73c
C)0.86c
D)0.81c
E)0.54c

Question

Quizplus · Accepted Answer

The correct answer is D.The astronaut's journey there and back took 6.3 years. So, the time taken for the journey to Alpha Centauri is 6.3/2 = 3.15 years. The distance to Alpha Centauri is 4.3 light-years. So, the speed of the astronaut is 4.3/3.15 = 1.36 light-years per year. This is equivalent to 0.81c.

Alpha Centauri Is Not Only the Closest Star System to Us