Velma and Mort pass each other, in rocket ships, at a relative velocity of half of lightspeed. Velma has an ice cream cone which will melt in 5 minutes if not refrigerated. She removes her cone from the refrigerator, and allows it to melt. According to Velma, how long does it take for her own cone to melt?
A) 5 minutes
B) more than 5 minutes
C) less than 5 minutes
D) It could be either more than 5 minutes, or 5 minutes, depending on which observer is at rest.

Question

Quizplus · Accepted Answer

The time dilation effect of special relativity states that moving clocks run slower than stationary clocks. In this case, Velma is moving relative to the ice cream cone, so her clock will run slower than the clock on the cone. This means that the cone will melt more slowly for Velma than it would for someone who was stationary relative to the cone. Therefore, it will take Velma more than 5 minutes to melt her cone.

Velma and Mort Pass Each Other, in Rocket Ships, at a Relative