Riding a bicycle on a flat, smooth surface is a lot easier than riding it along a bumpy surface or up a hill. A bumpy surface creates more friction with your bike tires than a smooth surface does, and going up a hill means fighting gravity. Write about a time you had to ride a bicycle on a difficult surface. What did you have to do to adjust your riding?

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