Question

Car A of mass 1500 kg travelling at 25 m/s collides with another car B of mass 1000 kg

travelling at 15 m/s in the same direction. After collision, the velocity of car A becomes 20 m/s.

Calculate the velocity of car B after collision.​

Answer 1

Momentum of system (before collision) = Momentum of system (after collision) { law of conservation of energy }

mu1(A) + mu2(B) = mv1(A) + mv2(B)

(1500×25) + (1000×15) = (1500×20)+(1000×v)

37500 + 15000 = 30000 + 1000v

52500 = 30000 = 1000v

22500 = 1000v

v = 22500/1000

v = 22.5 m/s