- #1

dyn

- 773

- 62

If a rigid disc rolls down an incline plane without slipping then the component of weight down the plane causes the disc to accelerate downwards but the frictional force causes a torque which causes the disc to rotate, At the point of rolling without slipping the velocity of the centre of mass is equal to Rω. Hopefully I'm right so far ? Now comes the part where I'm confused.

When rolling without slipping the point of the disc in contact with the plane is instantaneously at rest so the frictional force is zero. This means the torque is now zero and so the angular speed of rotation must remain constant. Is this correct ?

If this is correct this this must mean the velocity of the centre of mass which is still accelerating must become greater than Rω so the disc must start to slip again ?

This seems to imply the rolling without slipping condition cannot be maintained which seems wrong. Where am i going wrong ?

Thanks