Answers and Explanations

Review Questions

1. E
   The speed of light is constant to all observers, and thus all observers would measure the speed of the light as c.
2. C
   The length gets shorter (contracts) as the speed gets higher, so that the length it approaches zero at v = c.
3. E
   The traveling clock will have run more slowly than the Earth-bound clock, and thus more time will have passed on the Earth-bound clock than on the traveling clock.
4. D
   Some of the kinetic energy converts into mass as the speed of the object approaches the speed of light.