# Rolling constraints problem

1. Dec 4, 2006

### Logarythmic

How can I show that when a ball is rolling without slipping on a horizontal plane, the total horizontal force on the ball must be zero?

I guess I should consider the ball as a rigid body and combine the equations describing the rotation with the rolling constraints, but how? Can someone give me a starter here?

2. Dec 4, 2006

### Staff: Mentor

The statement is not correct. I think you meant to say that it is rolling at a constant velocity without slipping. If it's translational and rotational velocities are constant, then what can you say about F=ma?

But you can definitely accelerate a ball on a horizontal plane by applying a net force....

3. Dec 4, 2006

### Logarythmic

The problem says nothing about constant velocity, just that the ball is constrained to move on a horizontal plane. Otherwise, a = 0 and F = 0.

4. Dec 4, 2006

### KoGs

When the ball is not slipping, you can say something about the normal force.

5. Dec 4, 2006

### Logarythmic

Yeah, equal to mg?

6. Dec 6, 2006

### tim_lou

edit: nevermind.

Last edited: Dec 6, 2006