18. 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? ',, A " n_ 19. A car drives at steady speed v over the top of a circular- shaped hill of radius 50 m. What's the maximum speed the car can have without \"ying off\" the hill at the top? 20. A highway curves of radius 500 m is designed for trafc moving at a speed of 90 kin/hr. What is the correct banking angle of the road? (ans 1.6 s) 21. 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) 22. A satellite orbiting the moon very near the surface has a period of 110 min. What is freefall acceleration on the surface of the moon? (ans 1.58 111/52) 23. A 2 kg object is moving to the right with speed of 1 m/s when it experiences an impulse of -4 N 5. What are the objects's speed and direction after the impulse? (ans - 1 111/5) 24. At what speed do a bicycle and its rider, with a combined mass of 100 kg, have the same momentum as a 1500 kg car travelling at 5.0 m/s? (TB) 25. A small ball, light ball S and a large, heavy ball L move towards each other, collide, and bounce apart. a. Compare the force that S exerts on L during the collision to the force that L exerts on S. That is , is F S 0,, L, larger, smaller, or equal to FL 0,, 5? Explain. b. Compare the time interval during which S experiences a force to the time interval during which L experiences a force. Are they equal, or is one longer than the other? e. Sketch a graph showing a plausible F50, L as a anction of time and another graph showing a plausible F L 0,, S as a function of time. Be sure to think the sign of each force. (1. Compare the impulse delivered to S to the impulse delivered to L. Explain. e. Compare the momentum change of S to the momentum change of L