# Homework Help: Rolling motion

1. Feb 1, 2012

### physikx

1. The problem statement, all variables and given/known data
A uniform sphere rolls down a 30 degree incline θ from height h. Initially, the solid is at rest. Find the acceleration for the center of the mass of the solid.

I am not sure where to start with this problem. I started with the energy formulas, but I am not sure how to find the acceleration of the center of mass from there. I just need a guide on what formulas or setup to use, thanks!

2. Relevant equations
Translational and rotational motion equations

3. The attempt at a solution
K_i=mghsin30
K_f=1/2mv^2+1/2Iω^2

then I solved for v:

Last edited: Feb 1, 2012
2. Feb 1, 2012

### ehild

Hi, physikx,

The potential energy is mgh (h is the height of the (slope). Correct your result for v.

V is the speed of the CM at the end of the slope. Find the length travelled, and use the relation s=v^2/(2a) to determine the acceleration of the CM.

ehild

3. Feb 1, 2012

### physikx

Hey ehid,

Thank you so much for the help! I was able to setup the problem and get the answer. I really appreciate the guidance.

Peace

4. Feb 1, 2012

### ehild

You are welcome.

ehild