Question

A bowling ball has a mass of 4.55 kg.

What is the gravitational potential energy of the ball relative to ground if we raise it to a

height of 10.0 m?

If we drop the ball from an initial height of 10.0m, how fast will it be going when it hits

the ground?

How fast will the ball be going when it is halfway to the ground?

Answer 1

1)
Intial gravitational potential energy of the ball = Ui
= m*g*h
= 4.55*9.8*10.0
= 445.9 J

2)
when it reaches ground
let's its velocity be v
use,
Ui = 0.5*m*v^2
445.9 = 0.5*4.55*v^2
445.9 = 2.275*v^2
v^2 = 196
v = 14 m/s

it is going to hit with velocity 14 m/s

3)
when it will be halfway
it will have some potential energy m*g*5
use,
Ui + Ki = Kf + Uf
445.9 + 0 = 0.5*4.55*Vf^2 + 4.55*9.8*5
445.9 = 2.275*Vf^2 + 222.95
222.95 = 2.275*vf^2
vf^2 = 98
vf = 9.9 m/s
so,
speed at half way = 9.9 m/s