CHAPTER 7

1. (P.203 Prob.32) A 1500-kg car takes a 50-m-radius unbanked curve at 15 m/s. What is the size of the friction force on the car?
2. (P.203 Prob.40) A small ball rolls around a horizontal circle at height y inside the cone shown in Figure P7.40. Find an expression of the ball's speed in terms of a, h, y, and g.
   
3. (P.204 Prob.46) While at the county fair, you decide to ride the Ferris wheel. Having eaten too many candy apples and elephant ears, you find the motion somewhat unpleasant. To take your mind off your stomach, you wonder about the motion of the ride. You estimate the radius of the big wheel to be 15 m, and you use your watch to find that each loop around takes 25 s.
   a. What are your speed and magnitude of your acceleration?
   b. What is the ratio of your apparent weight to your true weight at the tip of the ride?
   c. What is the ration of your apparent weight to your true weight at the bottom?
4. (P.205 Prob.54) A 500 g steel block rotates on a steel table while attached a 2.0-m-long masssless rod. Compressed air fed through the rod is ejected from a nozzle on the back of the block, exerting a thrust force of 3.5 N. The nozzle is 70° from the radial line, as shown in Figure P7.54. The block starts from rest.
   a. What is the block's angular velocity after 10 rev?
   b. What is the tension in the rod after 10 rev?
   
5. (P.205 Prob.62) Challenge Problem. A 60 g ball is tied to the end of a 50-cm-long string and swung in a vertical circle. The center of the circle, as shown in Figure P7.62, is 150 cm above the floor. The ball is swung at the minimum speed necessary to make it over the top without the string going slack. If the string is released at the instant the ball is at the top of the loop, where does the ball hit the ground?