4th Edition

ISBN: 9780134899978

Author: Knight

Publisher: PEARSON

Concept explainers

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 69GP

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 68GP

Chapter 7, Problem 70GP

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Chapter 7 Solutions

COLLEGE PHYSICS, VOL. 1-W/ACCESS

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 - Prob. 5CQ Ch. 7 - Prob. 6CQ Ch. 7 - Prob. 7CQ 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 student gives a steady push to a ball at the end...

Ch. 7 - Prob. 11CQ Ch. 7 - If you grasp a hammer by its lightweight handle...Ch. 7 - Prob. 13CQ Ch. 7 - Prob. 15CQ Ch. 7 - The moment of inertia of a uniform rod about an...Ch. 7 - Prob. 17CQ 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 - Prob. 20MCQ Ch. 7 - Prob. 21MCQ Ch. 7 - Prob. 22MCQ Ch. 7 - Prob. 23MCQ Ch. 7 - A typical compact disk has a mass of 15 g and a...Ch. 7 - Two horizontal rods are each held up by vertical...Ch. 7 - Prob. 26MCQ 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 - Prob. 6P Ch. 7 - A turntable rotates counterclockwise at 78 rpm. A...Ch. 7 - Prob. 8P Ch. 7 - Prob. 9P Ch. 7 - Prob. 10P 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 - Prob. 14P Ch. 7 - A computer hard disk starts from rest, then speeds...Ch. 7 - Prob. 16P 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 - Prob. 19P Ch. 7 - Prob. 20P 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 - In Figure P7.22, force F2, acts half as far from...Ch. 7 - A professors office door is 0.91 m wide, 2.0 m...Ch. 7 - What is the net torque on the bar shown in Figure...Ch. 7 - Prob. 26P Ch. 7 - Prob. 27P Ch. 7 - Prob. 28P Ch. 7 - What is the net torque on the bar shown in Figure...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 - Prob. 35P Ch. 7 - Hold your arm outstretched so that it is...Ch. 7 - Prob. 37P Ch. 7 - Prob. 38P Ch. 7 - A regulation table tennis ball is a thin spherical...Ch. 7 - Prob. 40P Ch. 7 - A solid cylinder with a radius of 4.0 cm has the...Ch. 7 - Prob. 42P Ch. 7 - A bicycle rim has a diameter of 0.65 m and a...Ch. 7 - Prob. 44P Ch. 7 - A small grinding wheel has a moment of inertia of...Ch. 7 - Prob. 46P Ch. 7 - An objects moment of inertia is 2.0 kg m2. Its...Ch. 7 - Prob. 48P Ch. 7 - A 200 g, 20-cm-diameter plastic disk is spun on an...Ch. 7 - Prob. 50P Ch. 7 - A frictionless pulley, which can be modeled as a...Ch. 7 - Prob. 52P Ch. 7 - If you lift the front wheel of a poorly maintained...Ch. 7 - Prob. 54P Ch. 7 - A toy top with a spool of diameter 5.0 cm has a...Ch. 7 - Prob. 56P Ch. 7 - A bicycle with 0.80-m-diameter tires is coasting...Ch. 7 - Prob. 58P Ch. 7 - Prob. 59P Ch. 7 - Prob. 60P Ch. 7 - Prob. 61GP 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 - Prob. 68GP Ch. 7 - A reasonable estimate of the moment of inertia of...Ch. 7 - Prob. 70GP 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 - Prob. 76GP 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 - Prob. 81MSPP Ch. 7 - Prob. 82MSPP Ch. 7 - Prob. 83MSPP Ch. 7 - Prob. 84MSPP

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