試題詳解

12. A car of mass 1500 kg collides head-on with a parked truck of mass 3000 kg. Spring mounted bumpers ensure that the collision is essentially elastic. If the velocity of the truck is 18 km/h (in the same direction as the car's initial velocity) after the collision, what was the initial speed of the car?
(A) 18 km/h
(B) 38km/h
(C) 27km/h
(D) 10km/h
(E) 54km/h