A 1.0-kg ball on the end of a string is whirled at a constant speed of 2.0 m/s in a horizontal circle of radius 1.5 m. What is the work done by the centripetal force during one revolution?

Question

I did:
F=m(v^2)/r
F=1(2^2)/1.5=2.7 J

The answer that was provided was 0. Can someone explain the reasoning? Thanks

Answer 1

It seems to me that centripetal force is directed inward, but the direction of travel is tangent to the circle. How can a force ninety degrees to travel do any work?

Answer 2

There is no displacement in the direction of the force.
work=force * displacement in the direction of the force.

Answer 3

The object has no displacement during that time, therefore no work is done. Plus the ball traveled at a constant speed which makes the accleration zero, the force zero, and the work zero.

Answer 4

Work is transferred, not made.

Answer 5

If you look at the final displacement after a full revolution, it will be back where it started. Since work is Force dot Displacement, since displacement is zero, so is work.