Question

A 2.00 kg rock is dropped from the top of a 30.0 m high building. Calculate the ball’s momentum at the time that it strikes the ground.

Answer 1

Explanation:

We use the Theorem of conservation of mechanical energy for finding the velocity when it strikes the ground:

Ei = Ef

Ki + Ui = Kf + Uf

Ui = Kf

m g h = 1/2 m v^2

v = sqrt(2gh)

So the momentum will be:

p = mv = m * sqrt(2gh)