1- Relative to the Earth, spaceship A moves in one direction with speed 0.8c and another spaceship, B, moves in the opposite direction with speed 0.6c. What is the speed of spaceship A as measured by B? 2- A point moves with constant speed t in a direction which forms an angle with the x-axis of the frame of reference S'. Frame S' moves with a velocity V = V relative to another frame of reference Ss. What is the angle 0 formed by the direction of motion of the point with the x-axis of S? What is the relationship between the two angles as v - c? f sin sin d Ans.: tan 0 = tan e