# Homework Help: Kinetic energy of a ball roll

1. Feb 22, 2009

### physicsman2

1. The problem statement, all variables and given/known data
explain how an experiment where you let the ball roll from a certain height only models dropping a ball and finding its kinetic energy just as it hits the ground

2. Relevant equations
KE=PE
1/2mv^2=mgh

i dont think you need to utilize these equations

3. The attempt at a solution
i think since you already do work on the ball by putting it at a certain height and allowing it to roll down, there is no potential gravitational energy and since it is going to the ground, it is gaining kinetic energy, therefore kinetic energy can be found

2. Feb 22, 2009

### LowlyPion

First of all of course there is gravitational potential energy. Whatever the work that got the ball there isn't really of concern.

What is of interest though is the conservative nature of a gravitational field. Perhaps you should explore that for a moment?

3. Feb 22, 2009

### djeitnstine

You are correct

edit: @ Lowly

4. Feb 22, 2009

### physicsman2

so since you start out with a set amount of potential energy from the work done on the ball, the only thing the experiment is helping you find is the kinetic energy of the ball

is this how i could answer the question