Question

A car of mass 1200kg falls a vertical distance of 24m starting from rest what is the workdone by the force of gravity on the car?Use the work energy theorem to find the final velocity of the car just before it hits the water(Treat the as a point like object)

Answer 1

PE (relative to water) = M g h

PE = 1200 kg * 9.8 m/s^2 * 24 m = 2.82E5 Joules

KE = PE when vehicle strikes water

1/2 M V^2 = 2.82E5

V = (2.82E5 * 2 / 1200)^1/2 = 21.7 m/s

Check:

M g h = 1/2 M V^2

V = (2 g h)^1/2 = (2 * 9.8 * 24)^1/2 = 21.7 m/s