A car (mass = 1070 kg) is traveling at 40 m/s when it collides head-on with a sport utility vehicle (mass = 2570 kg) traveling in the opposite direction. In the collision, the two vehicles come to a halt. At what speed was the sport utility vehicle traveling?

Answer 1

if they come to a halt, then the total momentum is zero, and since it was conserved, the original momenum was zero.

MV+mv=0
V=-mv/M