Chapter 36, Problem 71GP

A spacecraft (reference frame S′) moves past Earth (reference frame S) at velocity $\stackrel{\to }{v}$, which points along the x and x′ axes. The spacecraft emits a light beam (speed c) along its y′ axis as shown in Fig. 36–17. (a) What angle θ does this light beam make with the x axis in the Earth’s reference frame? (b) Use velocity transformations to show that the light moves with speed c also in the Earth’s reference frame. (с) Compare these relativistic results to what you would have obtained classically (Galilean transformations).

FIGURE 36–17

Problem 75.