d) Draw the direction of the centripetal acceleration on your free body diagram. e) Why does the tension force in the string not do any work as the ball moves along its circular path? 6. A ride at the circus consists of a rotating circular cylinder of diameter D = 9.0 m. Riders stand against the wall and when the ride gets up to full rotational speed, the floor drops away. The frictional force between the person and the wall keeps him/her from sliding down the wall. At full rotational speed, the tangential speed of the rider is v = 12.0 m/s. a) What is the centripetal acceleration of a rider when the cylinder is at full rotational speed? b) What is the centripetal force on a rider of mass 85 kg? What force causes the centripetal force? c) What is the minimum static coefficient of friction that must exist between the rider and the wall to keep him/her from sliding down the wall when the floor is dropped down? Include a free body diagram as part of your solution. 7. A satellite orbits the Earth 15 times per day. a) How long does it take the satellite to complete a single orbit? Give your answer in seconds. b) At what height above the Earth’s surface does this satellite orbit? c) What speed does the satellite have?