Peter knocks a book off the 0.9 m-high table and it falls to the floor. Karin picks it up and places it back on the table. What is the total change in the gravitational potential energy of the book?
A. *delta*Ug = 0 J
B. *delta*Ug = 2 |mg| (0.9 m)
C. *delta*Ug = -mv 2

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 8.13 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 6.04 rev/s. (a) which rate of rotation gives the greater speed for the ball? 6.04 rev/s 8.13 rev/s (b) what is the centripetal acceleration of the ball at 8.13 rev/s? m/s2 (c) what is the centripetal acceleration at 6.04 rev/s? m/s2