Question

What is distance and displacement of ball which move in circular path of radius r

Answer 1

In one complete revolution, path covered is the circumference of the circle, that is, 2πr.

Therefore distance travelled is 2πr

Displacement is the perpendicular distance between the starting and the ending points. Here, since the starting and ending points are the same (as the particle came back to its original position after the revolution), the displacement is zero.