Dear All, I have learned that if a wheel is rolling without slipping, then the velocity of point of contact of a wheel with respect to the ground is zero instantaneously. However, I am having some problems while trying to understand that. We can express the point of contact's velocity as; V = Vrot + Vtrans It is zero because simply Vrot = -Vtrans. But after that instant, the point moves and an adjacent point becomes the point of contact -- thus rolling appears. If the point's velocity is zero, then it should stay at the bottom as the point of contact. And if it stays at / as point of contact, its velocity should still be zero. There is a circular logic here; How does it move if its velocity is zero ? And how does it have velocity greater than zero if it doesn't move ? ( since Vrot = -Vtrans if it stays at the bottom, its velocity would be zero.) Thanks in advance.