Question

answer plz..................

Answer 1

Depends on the final velocity, which is not given. If we assume the system is such that there are no outside forces, then momentum is conserved is that a good assumption you will have to decide from the context. If so then conservation of momentum will give you the final velocity and the kinetic energy equations will tell you the loss in kinetic energy (add up the total KE before and subtract the total KE after the collision.)