The tip of the second hand of a clock moves in a circle of 20 cm circumference. in one minute the hand makes a complete revolution. its average velocity over that time is cm/s.

Explanation:

As we know that average velocity is defined as the ratio of total displacement of the object and its time interval.

so here we can say

now we know that in one complete revolution the total displacement of the tip of the seconds hand is zero

because it will have same position after one complete revolution from where it starts

so here we can say that the average velocity will be zero