Question

) A 1000 kg car travelling at 50 m/s slams into a 1500 kg parked truck in an inelastic manner as

shown below. What is the velocity of the each after the collision?

Answer 1

(a)

KE = m v^2 / 2 = (1200 kg)(20 m/s)^2 / 2 = 240,000 J


(b)

The energy is entirely dissipated by the force of friction in the brake system.


(c)

W = delta KE = KEf - KEi = (0 - 240,000) J = -240,000 J



(d)

Fd = delta KE

F = (delta KE) / d = (-240,000 J) / (50 m) = -4800 N

The magnitude of the friction force is 4800 N.