At what speed is the momentum of an object double that found classically?
A)c/2
B)3c/4
C)0.866c
D)2c

Question

Quizplus · Accepted Answer

According to special relativity, momentum is proportional to velocity. The formula for momentum in special relativity is p=mv/sqrt(1-v^2/c^2). If we double the momentum, we can solve for the new velocity v' that will give us that doubled momentum. 2p=p'=mv'/sqrt(1-v'^2/c^2). Solving for v', we get v' = 0.866c. Therefore, the speed at which the momentum is double the classical value is 0.866c.

At What Speed Is the Momentum of an Object Double