An observer on Earth sees a rocket travelling away from Earth at a speed of
PHYSICS · Multi-part · A Level · Physics · Turning points in physics · Turning points in physics
Problem
An observer on Earth sees a rocket travelling away from Earth at a speed of 0.7c. The rocket fires a projectile forwards at a speed of 0.3c relative to it.
(1) a** Calculate the speed that the observer on the Earth measures for the projectile.
(2) b** Suppose that, instead of firing a projectile, the rocket fired a laser. By calculating the speed that the observer on the Earth measures for the leading edge of the laser beam from the rocket, show that the relativistic addition of velocities is consistent with the second postulate of relativity.