SAT Subject Physics Practice Question 151: Answer and Explanation

Next steps

Question: 151

14. A particle whose rest energy is E is traveling at a speed of c. What is the particle’s kinetic energy?

A.
B.
C.
D.
E.

Correct Answer: D

Explanation:

Because v is close to c, the particle is relativistic, so it would be incorrect to use the formula KE = mv2. Instead, we must use the formula KE = (γ – 1)mc2. Since v = c, the relativistic factor is

So, the kinetic energy of this particle is

Previous       Next