A railroad freight car,mass 16,000 kg,is allowed to coast along a level track at a speed of 2.0 m/s.It collides and couples with a 48,000-kg loaded second car,initially at rest and with brakes released.What percentage of the initial kinetic energy of the 16,000-kg car is preserved in the two-coupled cars after collision?

Question

Quizplus · Accepted Answer

The initial kinetic energy of the 16,000 kg car is 32,000 J. After the collision, the combined mass is 64,000 kg moving at 0.5 m/s, giving a kinetic energy of 8,000 J. The percentage preserved is (8,000/32,000) * 100% = 25%.

A Railroad Freight Car,mass 16,000 Kg,is Allowed to Coast Along