Review CHAPTER 3
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CHAPTER 3 RevIew K/U Knowledge/Understanding T/I Thinking/Investigation C Communication A Application Knowledge 6. Which of the following causes merry-go-round riders For each question, select the best answer from the four to feel as if they are being pushed away from the alternatives. centre of the ride? (3.4) K/U (a) being in an inertial reference frame 1. Which of the following describes an inertial frame (b) the Coriolis force of reference? (3.1) K/U (c) centripetal acceleration (a) one in which Newton’s first law of motion holds true (d) centrifugal force (b) one in which Newton’s first law of motion does Indicate whether each statement is true or false. If you think not apply the statement is false, rewrite it to make it true. (c) one in which Newton’s second law of motion no longer applies 7. An amusement park ride moving down with a constant velocity is an example of a non-inertial (d) one in which Newton’s third law of motion no frame of reference. (3.1) K/U longer applies 8. The law of inertia does not hold in a non-inertial 2. Which of the following is an example of a non- frame of reference. (3.1) K/U inertial frame of reference? (3.1) K/U (a) a spinning centrifuge 9. The direction of centripetal acceleration for a car on a banked curve is always down the incline parallel to (b) a digital clock on a moving bus the road surface. (3.2) K/U (c) an airplane moving with a constant velocity 10. The magnitude of an object’s centripetal acceleration (d) a stationary DVD increases with the mass, the radius of the circular 3. Which of the following describes an object that path, and the velocity of the object. (3.2) K/U follows a circular path at a constant speed? (3.2) K/U 11. An observer looking down on a passenger in a car (a) inertial motion driving around a sharp curve would see that the (b) uniform circular motion passenger is being pushed by the car in the direction (c) motion with constant acceleration of the curve. (3.3) K/U A (d) motion with constant velocity 12. The Moon is not an example of an object in uniform 4. Which of the following would result if a tetherball circular motion. (3.4) K/U A on a rope came off the rope midway through its path 13. Objects moving in a rotating frame of reference around the pole? (3.3) K/U A experience a force parallel to the velocity of the object (a) The ball would continue its circular path around in the rotating frame. (3.4) K/U the pole, eventually dropping with the force 14. A Foucault pendulum demonstrates that Earth is not of gravity. a rotating frame of reference. (3.4) K/U (b) The ball would fly away from the pole in the 15. A roller coaster car in free fall has no apparent straight-line direction it was travelling at the weight. (3.4) K/U A moment it came off the rope. (c) The ball would drop to the ground at the moment Write a short answer to each question. it came off the rope. 16. You are swinging your keys at the end of a lanyard (d) The ball would continue to move in its circular in a horizontal circle around your head. What is the path around the pole but with a decreasing radius. effect on the magnitude of the centripetal acceleration 5. In which of the following directions is the centripetal of the keys in each case? (3.2) K/U force acting on an object undergoing circular motion? (a) You keep the radius of the circle constant but (3.3) K/U double the speed. (a) in a straight line away from the centre of the (b) The speed of the keys stays the same, but you object’s path double the radius of the circle. (b) in a straight line away from the object at 17. Two cars with the same mass are driving around a 8 a 90 angle curved road at different velocities. Which car will (c) toward the centre of the circular path experience a greater centripetal force, the one moving (d) along the object’s path with the faster velocity or the one moving with the slower velocity? (3.3) K/U A 140 Chapter 3 • Uniform Circular Motion NEL 8160_CH03_p135-157.indd 140 4/26/12 9:55 AM 18. How are centrifuges used in blood analysis? 22. You are operating a remote-controlled car around a (3.4) K/U C circular path in an open field. The car is undergoing 2 19. Identify the force that is causing the centripetal force centripetal acceleration of 33.8 m/s . The radius of in each situation. (3.3, 3.4) K/U the car’s path is 125 m. Calculate the car’s speed. K/U T/I A (a) the Moon orbiting Earth (3.2) (b) a car turning a corner 23. WindSeeker, a 30-storey swing ride at Canada’s (c) a rock twirled on the end of a string Wonderland, ascends 91.7 m, spreads its metal arms, and swings riders at speeds up to 50.0 km/h. Understanding Calculate the ride’s centripetal acceleration when the ride operates at maximum speed and at full swing 20. While riding in a car heading east, you hold an with a diameter of 33.5 m. (3.2, 3.3) K/U T/I A accelerometer in your hand, like the one in Figure 1. 24. The track near the top of your favourite roller coaster The angle of the bead changes with the acceleration is looped with a diameter of 20 m. When you are at K/U T/I C of the car. (3.1) the top, you feel as if you weigh one-third of your vertical true weight. How fast is the roller coaster moving? K/U T/I A 80 (3.3) 80 70 60 70 50 60 25. A locomotive engine of mass 3m, pulling an empty 40 50 30 40 20 30 cargo car of mass m, is making a turn on a track. 10 0 10 20 Assuming that the engine and cargo car are moving at the same speed, compare the centripetal forces acting bead on each. Explain your answer. (3.3) K/U T/I A 26. You are riding on Air Gliders, a thrill ride at Calaway Figure 1 Park, Calgary, that swings riders around in a circle while (a) How must you hold the accelerometer so that metal arms move the cars up and down. (3.3) K/U T/I A it correctly measures acceleration? Explain (a) What is the centripetal force experienced by a your answer. 90 kg rider swinging around at 20 m/s in a circle (b) Describe what happens to the bead when the with a 16 m radius? vehicle is at rest. (b) Calculate the force when the ride’s arms close to (c) Describe what happens to the bead when the a radius of 10 m. vehicle is accelerating toward the east. (c) Calculate the force when the ride slows to 5 m/s, (d) Describe what happens to the bead when the keeping the radius at 10 m. vehicle is moving with a constant velocity. 27. A discus thrower at a track meet hurls a 2.0 kg (e) Describe what happens to the bead when the discus. She exerts a horizontal force of 2.8 3 102 N vehicle begins to slow down while moving toward on it as she spins. She rotates the disc, with her arm the east. outstretched, in uniform circular motion, with a (f) The bead is at an angle of 138 from the vertical. radius of 1.00 m. How fast will the discus travel Calculate the magnitude of the car’s acceleration. when released? (3.4) K/U T/I A 21. Determine the magnitude of the centripetal 28. A 2.0 kg jewellery box is sitting at the edge of acceleration in each scenario. (3.2) K/U T/I A a rotating shelf in a mechanical display case. (a) A penny is 13 cm from the centre of a vinyl The radius of the rotating shelf is 0.50 m. record. The record is playing on a turntable at Calculate the centripetal force when 33.5 rpm. (a) the shelf is rotating at 1.0 rpm (b) A rodeo performer is twirling his lasso with (b) the shelf frequency increases to 5.0 rpm uniform circular motion. One complete (c) the shelf frequency decreases to 0.50 rpm revolution of the rope takes 1.2 s. The distance (3.3, 3.4) K/U T/I A from the end of his rope to the centre of the circle 29. On the Drop Tower at Canada’s Wonderland, riders is 4.3 m. free-fall 23 storeys at speeds close to 100 km/h. (c) An electron is travelling around a nucleus at At some point during the ride, a person experiences 2.18 3 106 m/s. The diameter of the electron’s a force equivalent to 2g and the ride’s seat is pushing 2 orbit is 1.06 3 10 10 m. up with a force of 1.1 3 103 N. What is the person’s weight at this point? (3.4) K/U T/I A NEL Chapter 3 Review 141 8160_CH03_p135-157.indd 141 4/26/12 9:55 AM Analysis and Application 35.