Asked by Marisol

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?

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
Answered by bobpursley
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?
Answered by Quidditch
There is no displacement in the direction of the force.
work=force * displacement in the direction of the force.
Answered by Coconut
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.
Answered by Samuel
Work is transferred, not made.
Answered by Michael
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.