College Physics
2nd Edition
ISBN: 9780134601823
Author: ETKINA, Eugenia, Planinšič, G. (gorazd), Van Heuvelen, Alan
Publisher: Pearson,
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Chapter 9, Problem 35P
* Elena, a black belt in tae kwon do, is experienced in breaking boards with her fist. A high-speed video indicates that her forearm is moving with a rotational speed of 40 rad/s when it reaches the board. The board breaks in 0.0040 s and her arm is moving at 20 rad/s just after breaking the board Her fist is 0.32 m from her elbow joint and the rotational inertia of her forearm is
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Chapter 9 Solutions
College Physics
Ch. 9 - Review Question 9.1 Visualize an ice skater...Ch. 9 - Review Question 9.2 A solid wooden ball and a...Ch. 9 - Review Question 9.3 How is Newton’s second law for...Ch. 9 - Review Question 9.4 After a playground...Ch. 9 - Review Question 9.5 Will a can of watery chicken...Ch. 9 - Review Question 9.6 How can you explain the...Ch. 9 - Is it easier to open a door that is made of a...Ch. 9 - 2. You push a child on a swing. Why doesn’t the...Ch. 9 - In terms of the torque needed to rotate your leg...Ch. 9 - Suppose that two bicycles have equal overall mass,...
Ch. 9 - When riding a 10-speed bicycle up a hill, a...Ch. 9 - 6 The objects in Figure Q9.6 are made or two...Ch. 9 - 7. Select all the pairs below in which the two...Ch. 9 - If you turn on a coffee grinding machine sitting...Ch. 9 - A bowling ball is rolling without skidding down an...Ch. 9 - 10. The Mississippi River carries sediment from...Ch. 9 - Two disks are cut from the same uniform board. The...Ch. 9 - A spinning raw egg, if stopped momentarily and men...Ch. 9 - Compare the magnitude of Earth's rotational...Ch. 9 - You lay a pencil on a smooth desk (ignore sliding...Ch. 9 - If you watch the dive of an Olympic diver, you...Ch. 9 - 17. Explain why you do not tip over when riding a...Ch. 9 - Prob. 18CQCh. 9 - 19. Why do tightrope walkers carry long, heavy...Ch. 9 - The sweeping second hand on your wall clock is 20...Ch. 9 - 2. You find an old record player in your attic....Ch. 9 - 3. * Consider again the turntable described in the...Ch. 9 - 4. You step on the gas pedal in your car, and the...Ch. 9 - You pull your car into your driveway and stop. The...Ch. 9 - 6. An old wheat-grinding wheel in a museum...Ch. 9 - Centrifuge A centrifuge at the same museum is used...Ch. 9 - Potters wheel A fly sits on a potters wheel 0.30 m...Ch. 9 - 9. * During your tennis serve, your racket and arm...Ch. 9 - 10. * An ant clings to the outside edge of the...Ch. 9 - 11. * The speedometer on a bicycle indicates that...Ch. 9 - * You pedal your bicycle so that its wheel's...Ch. 9 - Mileage gauge The odometer on an automobile...Ch. 9 - *Speedomter The speedometer on an automobile...Ch. 9 - 15 * Ferns wheel A Ferris wheel starts at rest,...Ch. 9 - 16. * You push a disk-shaped platform tangentially...Ch. 9 - s rotational acceleration would be in ran/s2 if...Ch. 9 - 18. A 0.30-kg ball is attached at the end or a...Ch. 9 - 19. Centrifuge A centrifuge with a rotational...Ch. 9 - Airplane turbine what is the average torque needed...Ch. 9 - * A turntable turn ng at rotational speed 33 rpm...Ch. 9 - 22. * The solid pulley in Figure P9.22 consists...Ch. 9 - * The pulley shown in Figure P9.22 is initially...Ch. 9 - The pulley shown in Figure P9.22 is initially...Ch. 9 - 28. Derive an expression Tor the rotational...Ch. 9 - * Repeat the previous problem for an axis...Ch. 9 - Repeat the previous problem for axis BC, which...Ch. 9 - 31. * Merry-go-round A mechanic needs to replace...Ch. 9 - 32. * A small 0.80-kg train propelled by a fan...Ch. 9 - * Motor You wish to buy a motor that will be used...Ch. 9 - 34. ** A string wraps around a 6.0-kg wheel of...Ch. 9 - * Elena, a black belt in tae kwon do, is...Ch. 9 - Prob. 36PCh. 9 - 37. * Fire escape A unique fire escape for a...Ch. 9 - 38. ** An Atwood machine is shown in Example 9.4 ....Ch. 9 - onTruckandF2onbucket that the rope exerts on the...Ch. 9 - * A thin rod of length L and mass m rotates around...Ch. 9 - 41. * (a) Determine the rotaticnal momentum o’ a...Ch. 9 - Ballet A ballet student with her arms and a leg...Ch. 9 - * A 0.20-kg block moves at the end of a 0.50-m...Ch. 9 - * Puck on a string You attach a 100-g puck to a...Ch. 9 - 0. The student then turns the bicycle wheel over...Ch. 9 - 47. Neutron star An extremely dense neutron star...Ch. 9 - 48. * A boy of mass m is standing on the edge of a...Ch. 9 - 50. A grinding wheel with rotational inertia I...Ch. 9 - * The rotational speed of a flywheel increases by...Ch. 9 - B,/KrotA.Ch. 9 - * Flywheel energy for car The U.S. Department of...Ch. 9 - * Flywheel energy Engineers at the University of...Ch. 9 - 56. ** Rotating student A student sitting on a...Ch. 9 - * A turntable whose rotational inertia is...Ch. 9 - 58. **Repeat the previous problem, only assume...Ch. 9 - * Merry-go-round A carnival merry-go-round has a...Ch. 9 - *Est You hold an apple by its stem between your...Ch. 9 - * Stopping Earths rotation Suppose that Superman...Ch. 9 - BIO EST Punting a football Estimate the tangential...Ch. 9 - * BIO Triceps and darts Your upper arm is...Ch. 9 - 66. * BIO Bowling At the start of your throw of a...Ch. 9 - 67. ** Bio Leg lift You are doing one-leg leg...Ch. 9 - * A horizontal, circular platform can rotate...Ch. 9 - 69. * You have an empty cylindrical metal can and...Ch. 9 - ** in the previous problem, each nut has a mass of...Ch. 9 - 71. * Superball If you give a superball backspin...Ch. 9 - Prob. 72GPCh. 9 - 73. * EST White dwarf A star the size of our Sun...Ch. 9 - Tidal energy Tides are now used so gene-ate...Ch. 9 - Tidal energy Tides are now used so gene-ate...Ch. 9 - Tidal energy Tides are now used so gene-ate...Ch. 9 - Tidal energy Tides are now used so gene-ate...Ch. 9 - Tidal energy Tides are now used so gene-ate...Ch. 9 - Tidal energy Tides are now used so gene-ate...
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- A competitive diver leaves the diving board and falls toward the water with her body straight and rotating slowly. She pulls her arms and legs into a tight tuck position. What happens to her rotational kinetic energy? (a) It increases. (b) It decreases. (c) It stays the same. (d) It is impossible to determine.arrow_forwardA disk with moment of inertia I1 rotates about a frictionless, vertical axle with angular speed i. A second disk, this one having moment of inertia I2 and initially not rotating, drops onto the first disk (Fig. P10.50). Because of friction between the surfaces, the two eventually reach the same angular speed f. (a) Calculate f. (b) Calculate the ratio of the final to the initial rotational energy. Figure P10.50arrow_forwardBig Ben, the Parliament tower clock in London, has an hour hand 2.70 m long with a mass of 60.0 kg and a minute hand 4.50 m long with a mass of 100 kg (Fig. P10.17). Calculate the total rotational kinetic energy of the two hands about the axis of rotation. (You may model the hands as long, thin rods rotated about one end. Assume the hour and minute hands are rotating at a constant rate of one revolution per 12 hours and 60 minutes, respectively.) Figure P10.17 Problems 17, 49, and 66.arrow_forward
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Rotational Kinetic Energy; Author: AK LECTURES;https://www.youtube.com/watch?v=s5P3DGdyimI;License: Standard YouTube License, CC-BY