A car of mass 1500 kg traveling at 15.6 m/s loses its brakes and collides with the rear end of the car in front of it, which has a mass of 1020 kg and is traveling in the same direction at 12.5 m/s. If the smaller car is given a speed of 15.3 m/s by the collision, what is the speed of the larger car after the collision?

Answer 1

M1*V1 + M2*V2 = M1*V3 + M2*V4.
1500*15.6 + 1020*12.5=1500*V3+1020*15.3
23,400 + 12,750 = 1500V3 + 15,606.
36,150 = 1500V3 + 15,606.
1500V3 = 20,544.
V3 = 13.7 m/s.