PROBLEMS FROM HRW PROBLEM SUPPLEMENT #1 and SERWAY JUNE 10 - JUNE 16 HRW PROBLEM SUPPLEMENT #1 - CHAPTER 6 49. A small coin is placed on a flat, horizontal turntable. The turntable is observed to make three revolutions in 3.14 s. (a) What is the speed of the coin when it rides without slipping at a distance of 5.0 cm from the center of the turntable? (b) What is the acceleration (magnitude and direction) of the coin? (c) What are the magnitude and direction of the frictional force acting on the coin if the coin has a mass of 2.0 g? (d) What is the coefficient of static friction between the coin and the turntable if the coin is observed to slide off the turntable when it is more than 10 cm from the center of the turntable? 61. A 26 kg child on a steadily rotating Ferris wheel moves at a constant speed of 5.5 m/s around a vertical circular path of radius 12 m. What are the magnitude and direction of the force of the seat on the child (a) at the highest point of the path and (b) at the lowest point of the path? 70. A banked circular highway curve is designed for traffic moving at 60 km/h. The radius of the curve is 200 m. Traffic is moving along the highway at 40 km/h on a rainy day. What is the minimum coefficient of friction between tires and road that will allow cars to take the turn without sliding off the road? SERWAY - CHAPTER 5 46. A ball is suspended from the ceiling of a moving car by a string 25 cm in length. An observer in the car notes that the ball deflects 6 cm from the vertical toward the rear of the car. What is the acceleration of the car? SERWAY - CHAPTER 7 22. When a 4-kg mass is hung vertically on a certain light spring that obeys Hooke's law, the spring stretches 2.5 cm. If the 4-kg mass is removed, (a) how far will the spring stretch if a 1.5-kg mass is hung on it, and (b) how much work must an external agent do to stretch the same spring 4.0 cm from its unstretched position? 26. If it takes 4 J of work to stretch a Hooke's-law spring 10 cm beyond its unstressed length, determine the additional work required to stretch it another 10 cm. SERWAY - CHAPTER 8 56. A 10-g mass is attached to the end of an unstressed, light, vertical spring (k = 49 N/m) and then dropped. Answer the following questions by considering the potential energy due to the spring plus the potential energy due to gravity, i.e. measure distances from the equilibrium position of the spring with no mass attached. (a) What is the maximum speed of the falling mass? (b) How far does the mass drop before coming to rest momentarily? (c) Repeat (a) and (b), but answer the questions by considering the potential energy of the spring with the mass attached, i.e. measure distances from the equilibrium position of the spring with the mass attached.