# Homework Help: Mastering physics :/

1. Mar 7, 2005

### RhysticGenesis

Ok here is the problem A hollow spherical shell with mass 2.50kg rolls without slipping down a slope that makes an angle of 30.0 degrees with the horizontal.
> Find the acceleration a_cm of the center of mass of the spherical shell.
> Take the free-fall acceleration to be g=9.80m/s^2.
> I got 24.2068 but again I was wrong

- I though it was mgsin(theta) was it not?

> Find the frictional force acting on the spherical shell.
Im not sure but wouldnt it be coefficient of friction (which I do not know) times the normal force (which would be the answer to the above I think?)

Another problem is :
A circular hoop of mass m, radius r, and infinitesimal thickness rolls without slipping down a ramp inclined at an angle theta with the horizontal. View Figure