3rd Edition

ISBN: 9780321989246

Author: Knight

Publisher: PEARSON CO

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Torque is the rotational equivalent of linear force in physics and mechanics. Based on the course of study, it is also known as the moment of force, rotational force, or turning effect.

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Textbook Question

Chapter 7, Problem 63GP

A reasonable estimate of the moment of inertia of an ice skater spinning with her arms at her sides can be made by modeling most of her body as a uniform cylinder. Suppose the skater has a mass of 64 kg. One-eighth of that mass is in her arms, which are 60 cm long and 20 cm from the vertical axis about which she rotates. The rest of her mass is approximately in the form of a 20-cm-radius cylinder.

a. Estimate the skater’s moment of inertia to two significant figures.

b. If she were to hold her arms outward, rather than at her sides, would her moment of inertia increase, decrease, or remain unchanged? Explain.

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Chapter 7, Problem 62GP

Chapter 7, Problem 64GP

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Chapter 7 Solutions

EBK COLLEGE PHYSICS

Ch. 7 - The batter in a baseball game hits a home run. As...Ch. 7 - Viewed from somewhere in space above the north...Ch. 7 - Figure Q7.3 shows four pulleys, each with a heavy...Ch. 7 - If you are using a wrench to loosen a very...Ch. 7 - If you are using a wrench to loosen a very...Ch. 7 - A screwdriver with a very thick handle requires...Ch. 7 - If you have ever driven a truck, you likely found...Ch. 7 - A common type of door stop is a wedge made of...Ch. 7 - A student gives a steady push to a ball at the end...Ch. 7 - Prob. 10CQ

Ch. 7 - Prob. 11CQ Ch. 7 - If you grasp a hammer by its lightweight handle...Ch. 7 - Suppose you have two identical-looking metal...Ch. 7 - The moment of inertia of a uniform rod about an...Ch. 7 - The wheel in Figure Q7.15 is rolling to the right...Ch. 7 - With care, its possible to walk on top of a barrel...Ch. 7 - A nut needs to be tightened with a wrench. Which...Ch. 7 - Suppose a bolt on your car engine needs to be...Ch. 7 - Prob. 19MCQ Ch. 7 - A typical compact disk has a mass of 15 g and a...Ch. 7 - Suppose manufacturers increase the size of compact...Ch. 7 - Two horizontal rods are each held up by vertical...Ch. 7 - Prob. 23MCQ Ch. 7 - A particle undergoing circular motion in the...Ch. 7 - Questions 25 through 27 concern a classic...Ch. 7 - Questions 25 through 27 concern a classic...Ch. 7 - Questions 25 through 27 concern a classic...Ch. 7 - What is the angular position in radians of the...Ch. 7 - A child on a merry-go-round takes 3.0 s to go...Ch. 7 - What is the angular speed of the tip of the minute...Ch. 7 - An old-fashioned vinyl record rotates on a...Ch. 7 - The earths radius is about 4000 miles. Kampala,...Ch. 7 - A Ferris wheel rotates at an angular velocity of...Ch. 7 - A turntable rotates counterclockwise at 78 rpm. A...Ch. 7 - A fast-moving superhero in a comic book runs...Ch. 7 - Figure P7.9 shows the angular position of a...Ch. 7 - The angular velocity (in rpm) of the blade of a...Ch. 7 - The 1.00-cm-long second hand on a watch rotates...Ch. 7 - The earths radius is 6.37 106 m; it rotates once...Ch. 7 - To throw a discus, the thrower holds it with a...Ch. 7 - A computer hard disk starts from rest, then speeds...Ch. 7 - The crankshaft in a race car goes from rest to...Ch. 7 - Reconsider the situation in Example 7.10. If Luis...Ch. 7 - Balls are attached to light rods and can move in...Ch. 7 - Six forces, each of magnitude either F or 2F, are...Ch. 7 - What is the net torque about the axle on the...Ch. 7 - The tune-up specifications of a car call for the...Ch. 7 - A professors office door is 0.91 m wide, 2.0 m...Ch. 7 - In Figure P7.22, force F2, acts half as far from...Ch. 7 - Tom and Jerry both push on the 3.00-m-diameter...Ch. 7 - What is the net torque on the bar shown in Figure...Ch. 7 - What is the net torque on the bar shown in Figure...Ch. 7 - What is the net torque on the bar shown in Figure...Ch. 7 - Prob. 27P Ch. 7 - Prob. 28P Ch. 7 - Hold your arm outstretched so that it is...Ch. 7 - Prob. 30P Ch. 7 - The 2.0 kg, uniform, horizontal rod in Figure...Ch. 7 - A 4.00-m-long, 500 kg steel beam extends...Ch. 7 - An athlete at the gym holds a 3.0 kg steel ball in...Ch. 7 - The 2.0-m-long, 15 kg beam in Figure P7.34 is...Ch. 7 - Two thin beams are joined end-to-end as shown in...Ch. 7 - Figure P7.36 shows two thin beams joined at right...Ch. 7 - A regulation table tennis ball is a thin spherical...Ch. 7 - Three pairs of balls are connected by very light...Ch. 7 - A playground toy has four seats, each 5.0 kg,...Ch. 7 - A solid cylinder with a radius of 4.0 cm has the...Ch. 7 - A bicycle rim has a diameter of 0.65 m and a...Ch. 7 - a. What is the moment of inertia of the door in...Ch. 7 - A small grinding wheel has a moment of inertia of...Ch. 7 - While sitting in a swivel chair, you push against...Ch. 7 - An objects moment of inertia is 2.0 kg m2. Its...Ch. 7 - A 200 g, 20-cm-diameter plastic disk is spun on an...Ch. 7 - The 2.5 kg object shown in Figure P7.47 has a...Ch. 7 - A frictionless pulley, which can be modeled as a...Ch. 7 - If you lift the front wheel of a poorly maintained...Ch. 7 - On page 207 there is a photograph of a girl...Ch. 7 - A toy top with a spool of diameter 5.0 cm has a...Ch. 7 - A bicycle with 0.80-m-diameter tires is coasting...Ch. 7 - Figure P7.55 shows the angular...Ch. 7 - The grap in Figure P7.56 shows the angular...Ch. 7 - A car with 58-cm-diameter tires accelerates...Ch. 7 - The cable lifting an elevator is wrapped around a...Ch. 7 - The 20-cm-diameter disk in Figure P7.59 can rotate...Ch. 7 - A combination lock has a 1.0-cm-diameter knob that...Ch. 7 - A 70 kg mans arm, including the hand, can be...Ch. 7 - The three masses shown in Figure P7.62 are...Ch. 7 - A reasonable estimate of the moment of inertia of...Ch. 7 - Starting from rest, a 12-cm-diameter compact disk...Ch. 7 - The ropes in Figure P7.65 are each wrapped around...Ch. 7 - Flywheels are large, massive wheels used to store...Ch. 7 - A 1.0 kg ball and a 2.0 kg ball are connected by a...Ch. 7 - A 1.5 kg block is connected by a rope across a...Ch. 7 - The two blocks in Figure P7.69 are connected by a...Ch. 7 - The 2.0 kg, 30-cm-diameter disk in Figure P7.70 is...Ch. 7 - A tradesman sharpens a knife by pushing it with a...Ch. 7 - MCAT-Style Passage Problems The Bunchberry The...Ch. 7 - The Bunchberry The bunchberry flower has the...Ch. 7 - The Bunchberry The bunchberry flower has the...Ch. 7 - The Bunchberry The bunchberry flower has the...Ch. 7 - Prob. 76MSPP Ch. 7 - Prob. 77MSPP Ch. 7 - Prob. 78MSPP

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