Question

If a 20 kg object fell to the surgace of the Earth from a height of 30m, what would its final velocity be? (work from the energy standpoint)

I know that you said it is F * X and I'm just confused. Can you help me walk through this?

Answer 1

Work is defined as force * distance. The force here is weight, or mg. Work done by gravity is then mgh.

Now, that work results in kinetic energy, 1/2 mv^2

1/2 m v^2=mgh
1/2 v^2=gh
v= sqrt 2gh