If spaceship A is travelling at 70% the speed of light relative to an observer at rest,and spaceship B is travelling at 90% the speed of light relative to an observer at rest,which of the following have the greatest velocity as measured by an observer in spaceship B?
A)A cannon shot from A to B at 50% the speed of light as measured in A's reference frame.
B)A ball thrown from B to A at 50% the speed of light as measured in B's reference frame.
C)A particle beam shot from a stationary observer to B at 70% the speed of light as measured in stationary reference frame.
D)A beam of light shot from A to B travelling at the speed of light in A's reference frame.
E)All of the choices have the same velocity as measured in B's reference frame.

Question

Quizplus · Accepted Answer

According to the theory of relativity, the speed of light is constant in all reference frames. Therefore, a beam of light shot from A to B will be measured to be traveling at the speed of light in B's reference frame. The other options involve objects moving at speeds that are relative to the observer, which means their velocities will be altered based on the observer's reference frame. Thus, a beam of light is the only option that is not subject to this alteration and will have the same velocity as observed from any reference frame.

If Spaceship a Is Travelling at 70% the Speed of Light