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Oct30-07, 01:32 PM
P: 4
Quote Quote by Jeff Reid View Post
Gravity pulls down on the hoop at it's center of mass. The pavement pushes up on the hoop at the point of contact. This creates an "inwards" torque. The torque creates an outward force at the point of contact with pavement. The pavement responds with and equal and opposite inwards (centripital force). This is what causes the hoop to change direction or follow a curved path...
But wouldn't exactly the same set of forces occur with a stationary hoop that's falling over? The component you're calling centripetal would just be a simple horizontal force in a stationary wheel so why does it cause a rolling wheel to change direction?
I'm still confused.