PHYSICS
posted by Blanca on .
An athlete swings a ball, connected to the end of a chain, in a horizontal circle. The athlete is able to rotate the ball at the rate of 7.80 rev/s when the length of the chain is 0.600 m. When he increases the length to 0.900 m, he is able to rotate the ball only 6.51 rev/s

I need to answer: What is the centripetal acceleration of the ball at 7.80 rev/s? and What is the centripetal acceleration at 6.51 rev/s?

Multiply the rev/s numbers by 2 pi to get radians per second, and call that w.
The centripetal accleration is R*w^2 in both cases. However, different R and w values apply in the two cases.
The centripetal acceleration value will be close for the two cases, but not quite the same.