PHYS 221 Sample questions chapter (8-11) . A toy car moves around a circular track at constant speed. The centripetal acceleration was found to be changed by a factor of 4. The changes in speed should be a factor of (2) (a) 1/4. (b) 1/2. (c) No change since the radius doesn't change. (d) 2. (e) 4. 2. A ball on a string moves in a vertical circle. When the ball is at its lowest point, the tension in the string greater than, less than, or equal to the ball's weight? Explain with free body diagram when the ball is at the bottom. (6) \\. . Figure shows two balls of equal mass moving in vertical circles. Is the tension in string A greater than, less than, or equal to the tension in string B if the balls travel over the top of the circle (a) with equal speed and (b) with equal angular velocity? . m 0 2r r U A " B A car drives at steady speed v over the top of a circular-shaped hill of radius 50 In. What's the maximum speed the car can have without \"ying off" the hill at the top? (ans 22m/s) . A highway curves of radius 500 m is designed for traffic moving at a speed of 90 krm'hr. What is the correct banking angle of the road? (ans 1.6 s) . A 100 g ball on a 60 cm long string is swung in a vertical circle about a point 200 cm above the oor. The string suddenly breaks when it is parallel to the ground and ball is moving upward. The ball reaches a height 600 cm above the oor. What was the tension in the string an instant before it broke? (ans 13 N) . A satellite orbiting the moon very near the surface has a period of 110 min. What is free-fall acceleration on the surface of the moon? (ans 1.58 mst)