Question

A railroad freight car, mass 15000 kg, is allowed to coast along a level track at a speed of 2.0 m/s. It collides and couples with a 50000 kg freight car, initially at rest and with brakes released. What percentage of the initial kinetic energy of the 15000 kg car is preserved in the coupled cars after collision

Answer 1

Step-by-step explanation:

Use conservation of momentum to find the final velocity

15000(2.0) + 50000(0) = (15000 + 50000)v

v = 0.461538461... = 0.46 m/s

KEf / KEi = ½65000(0.46²) / (½15000(2²) + ½50000(0²)) = 0.2307687...

KEf / KEi = 23%