A two-stage rocket moves in space at a constant velocity of 5100 m/s. The two stages are then separated by a small explosive charge placed between them. Immediately after the explosion the velocity of the 1250-kg upper stage is 5520 m/s in the same direction as before the explosion. What is the velocity (magnitude and direction) of the 2460-kg lower stage after the explosion?

answer should be in m/s

in the initial direction of flight opposite to the initial direction of flight

Use conservation of momentum.