A dynamics student is called on to investigate a two-car collision. It's known that car A struck car B. Mass of car A is 2000 kg and mass of car B is 1200 kg. Both Car A and B then skidded 8 meters. It appears from the damage that car A struck car B at a relative speed of 12 m/sec.
Find: the speed of car A just before the collision. Assume a purely plastic collision (e=0) and a coefficient of friction between the cars and the road of 0.7 .