Question

An enemy spaceship is moving toward your starfighter with a speed of 0.400 c , as measured in your reference frame. The enemy ship fires a missile toward you at a speed of 0.700 c relative to the enemy ship. If you measure the enemy ship to be 7.00×106 km away from you when the missile is fired, how much time t, measured in your frame, will it take for the missile to reach you

Answer 1

The answer is (a) 0.859c (b) 31s