# Circular motion of rigid body

1. Nov 19, 2008

### atavistic

When considering pure rotation of a rigid body about some point , then can we always consider the body to be concentrated in its centre of mass and use all force related equation treating it like a point object situated at it center of mass.? Why? Can anyone prove mathematically because there are many things like moment of inertia ,for e.g, for which we cannot do that.

2. Nov 19, 2008

### atavistic

BUMP please I really need this in a few hours.

3. Nov 19, 2008

### Staff: Mentor

I'm not sure I understand your question. If you're asking whether Newton's 2nd law for translation applies--sure:

$$\Sigma F = ma_{cm}$$

If that's not what you mean, please give a specific example of your concern.