1)The torque of the weight of any body about any vertical axis is 0. Is it always true? 2)A sphere rolls on a horizontal surface. Is there any point of the sphere which has a vertical velocity? 3) When several forces acts on a particle we take the torque of the resultant force. Is this result valid for the force acting on different particles of a body in such a way that their lines of action intersect at a common point ? 4)In pure rolling angular velocity is independent of the distance r from the axis of rotation. Why ?