139. Time Dilation 

Derivation of the time-dilation equation, and applications

End Question:

First, while you’re in a spaceship leaving Earth at half the speed of light you apply the time-dilation equation to two cases. First, measuring your own pulse rate; second, measuring the pulse rate of a friend at rest back on Earth. How will the values of v in the time dilation equation differ for the two cases, and what does this tell you about relative pulse rates?