# Concept of velocity of center of mass

Suppose a circular object is rolling along a straight line. I seem to have seem vaguely that tangential velocity of the point of contact is equal to the velocity of center of mass(or that sort of things i am not really sure).What does the velocity of point of contact has anything to do with center of mass? I see that this is a concept which i haven't been taught in my school books. I would like to learn more about this concept. So could the physics lovers kindly explain this concept intuitively or provide some sources where i could learn them?It would be a great help to me.

2. If in the roll's axis frame, the velocity of a point at the periphery is $$v$$, that is the same "velocity" of the ground, then in the frame of the ground, the velocity of the roll's axis must be $$-v$$.