A green 6kg ball is moving at 4 m/s. It collides with an orange 4 kg ball that is not moving (v= 0m/s). After the collision the green ball stops moving (v= 0m/s).

Question

What is the velocity of the orange ball after the collision?

A: 6 m/s

B: 4 m/s

C: 0 m/s

D: 8 m/s

Answer 1

Initial momentum p_i = (6 Kg)*(4 m/s). By conservation of momentum, p_f = p_i = 24 = (4 kg)*v_f and v_f = 6 m/s.