The movement of an object or a point mass at a constant speed around a circle that has a fixed radius is called uniform .

circular motion

Explanation:

A circular motion is defined as the movement of the object in a circular direction along a fixed point or the circumference of the circle. The circular motion of the object can be uniform circular motion, non uniform or variable circular motion.

For an object moving in a circular motion at a constant speed, the net force should always acts towards the center of the circle.

come closer and become far apart and become steam/gas

no. dot product   =0 when vecs at right angles