As measured from Earth, a second of time marked by a clock aboard a fast (hypothetical) interstellar ship moving at v = 0.95c would be ________ compared with the second marked by a clock at rest on Earth.
A) 70.71 times shorter
B) 70.71 times longer
C) 7.09 times shorter
D) 3.20 times longer
E) 3.20 times shorter

Question

Quizplus · Accepted Answer

Due to time dilation in special relativity, a clock moving at 0.95c will run slower compared to a clock at rest. The time dilation factor is given by the Lorentz factor, which is approximately 3.20 for v = 0.95c. Thus, the second on the moving clock is 3.20 times longer as measured from Earth.

As Measured from Earth, a Second of Time Marked by a Clock