Ball tied to string- centripetal force

[Dannystu]

Homework Statement

A ball, mass m = 1.5 kg is twirled at constant speed v at the end of a massless string in a vertical circle of radius r = 1.2 m. The period for this uniform circular motion is T = 1.3 s. Free body diagrams for the ball at the top and at the bottom of the circle are shown.
a. Compute the speed v of the ball.
b. Compute the ball’s centripetal acceleration.
c. Compute the “centripetal force” on the ball.
d. When the ball is at the top (point A in the figure) compute the tension FTA in the string.
e. When the ball is at the bottom (point B in the figure) compute the tension FTB in the string.

Homework Equations

I understand all the parts except for question c, is the formula for centripetal force m*(v^2/r)? Or is it the same as the The tension in the string?

 

[Doc Al]

I understand all the parts except for question c, is the formula for centripetal force m*(v^2/r)?

Yes.

Or is it the same as the The tension in the string?

No, they are not the same.

 

[Dannystu]

thanks a lot Doc!