Rolling wheel & points with total velocity equal to linear
When a wheel (circle (A, B)) is rolling without slipping on a smooth and flat surface there are a lot of its points that have the same total velocity (magnitude) as the velocity of its center of mass. By sliding point C of circle(A, C) (points in a random inner circle) you can see the two points (D by sliding sig) with such a property. You can also watch the vectors of linear (u) and tangential (v) velocity as well as the total velocity (w=u+v) which has the same magnitude as u. All these D points are on the circle(f).