Physics Problem #1?

Question

Please answer and show work...
A ball on the end of a string is revolved at a uniform rate in a vertical circle of radius 72.0 cm. If it's speed is 4.00 m/s, and its mass is .300 kg, calculatethe tension in the string when the ball is (a) at the topof its path, and (b) at the bottom of its path.

Answer 1

Acceleration in a circular path=V^2/r
V=tangential velocity of the mass
r=radius of circle.
Here the mass is moving in circular
path in a vertical circle. Hence the
gravity will come in to play. At the
top it will act against while at the
bottom it will add.
Acceleration on top
=V^2/r-g
=[4^2/.72]-9.81
=22.22-9.81
=12.41m/sec^2
Acceleration at bottom
=V^2+g
=[4^2/.72]+9.81
=22.22+9.81
=32.03 m/sec^2