# Acceleration of center of mass

A solid shere of mass M and radius R rolls without slipping down an inclined plane whose incline angle with the horizontal is 30 degrees. What is the acceleration of the sphere's center of mass?

gsinX is the acceleration, so it would be g/2 right?

Doc Al
Mentor
No. While $mg \sin \theta$ is the component of the ball's weight along the incline, it is not the only force acting on the ball.

A solid shere of mass M and radius R rolls without slipping down an inclined plane whose incline angle with the horizontal is 30 degrees.

still not sure what you mean... so it doesnt slip, so what?

Doc Al
Mentor
Start by identifying all the forces acting on the sphere. (Hint: I count 3)

force of friction, normal force, and force of gravity

Doc Al
Mentor
Right. To solve for the acceleration, you'll need to apply Newton's 2nd law for both translation and rotation.

HallsofIvy
The point of "rolling without slipping" is that the sphere makes on complete revolution while going a distance $2\pi R$