Question

A 730-kg car stopped at an intersection is rear-ended by a 1710-kg truck moving with a speed of 14.5 m/s .

If the car was in neutral and its brakes were off, so that the collision is approximately elastic, find the final speed of the truck.

Find the final speed of the car.

Answer 1

Given that,

mass of the truck = m1 = 1710 kg ;mass of the car = m2 = 730 kg ; v0 = 14.5 m/s

let Vt be the final speed of the truck and Vc be that of the car.

As the collision is elastic, so applying both the momentum and energy conservation, will give us the results:

Vt = (m1 - m2) vo / (m1 + m2)

Vt = (1710 - 730) x 14.5 / (1710 + 730) = 5.82 m/s

Vc = 2 m1 vo / (m1 + m2)

Vc = 2 x 1710 x 14.5 / (1710 + 730) = 20.32 m/s

Hence, thhe final speed of truck = Vt = 5.82 m/s and that of the car = Vc = 20.32 m/s.