12th Edition

ISBN: 9780321909107

Author: Paul G. Hewitt

Publisher: PEARSON

Concept explainers

A machine is a device that accepts energy in some available form and utilizes it to do a type of work. Energy, work, or power has to be transferred from one mechanical part to another to run a machine. While the transfer of energy between two machine par…

Kinetic Energy and Work-Energy Theorem

In physics, work is the product of the net force in direction of the displacement and the magnitude of this displacement or it can also be defined as the energy transfer of an object when it is moved for a distance due to the forces acting on it in the d…

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Textbook Question

Chapter 7, Problem 121RCQ

To combat wasteful habits, we often speak of “conserving energy,” by which we mean turning off lights and hot water when they are not being used and keeping thermostats at a moderate level. In this chapter, we also speak of “energy conservation.” Discuss and distinguish between these two phrases.

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Chapter 7, Problem 120RCQ

Chapter 7, Problem 122RCQ

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Chapter 7 Solutions

Conceptual Physics (12th Edition)

Ch. 7 - When is energy most evident?Ch. 7 - A force sets an object in motion. When the force...Ch. 7 - Cite an example in which a force is exerted on an...Ch. 7 - Prob. 4RCQ Ch. 7 - Exactly what is it that enables an object to do...Ch. 7 - If both sacks in the preceding question are lifted...Ch. 7 - A car is raised a certain distance in a...Ch. 7 - Two cars are raised to the same elevation on...Ch. 7 - When is the potential energy of something...Ch. 7 - Prob. 10RCQ

Ch. 7 - 11. Compared with a car moving at some original...Ch. 7 - If you push a crate horizontally with 100 N across...Ch. 7 - 13. How does speed affect the friction between a...Ch. 7 - 14. What will be the kinetic energy of a pile...Ch. 7 - An apple hanging from a limb has potential energy...Ch. 7 - 16. What is the source of energy in sunshine? Ch. 7 - Prob. 17RCQ Ch. 7 - 18. Can a machine multiply input force? Input...Ch. 7 - 19. If a machine multiplies force by a factor of...Ch. 7 - 20. A force of 50 N is applied to the end of a...Ch. 7 - 21. What is the efficiency of a machine that...Ch. 7 - Prob. 22RCQ Ch. 7 - Prob. 23RCQ Ch. 7 - Prob. 24RCQ Ch. 7 - 25. Can we correctly say that hydrogen is a new...Ch. 7 - Prob. 26RCQ Ch. 7 - Prob. 27RCQ Ch. 7 - Prob. 28RCQ Ch. 7 - Prob. 29RCQ Ch. 7 - Prob. 30RCQ Ch. 7 - Prob. 31RCQ Ch. 7 - Power = work/time: P = W / t 32. Show that 50 W of...Ch. 7 - 33. Show that about 786 W of power is expended...Ch. 7 - Prob. 34RCQ Ch. 7 - 35. Show that the gravitational potential energy...Ch. 7 - Kinetic energy= 1 2 mass X speed : KE= 1 2 m v 2...Ch. 7 - 37. Calculate the kinetic energy of an 84-kg...Ch. 7 - Work-energy theorem: Work = KE 38. Show...Ch. 7 - 39. Show that a 2,500,000-J change in kinetic...Ch. 7 - Prob. 40RCQ Ch. 7 - Prob. 41RCQ Ch. 7 - 42. (a) How much work is done when you push a...Ch. 7 - 43. This question is typical on some driver’s...Ch. 7 - Belly-flop Bernie dives from atop a tall flagpole...Ch. 7 - Nellie Newton applies a force of 50 N to the end...Ch. 7 - 46. Consider an ideal pulley system. If you pull...Ch. 7 - 47. In raising a 5000-N piano with a pulley...Ch. 7 - 48. In the hydraulic machine shown, you observe...Ch. 7 - 49. How many watts of power do you expend when you...Ch. 7 - Emily holds a banana of mass m over the edge of a...Ch. 7 - 51. The mass and speed of the three vehicles, A,...Ch. 7 - 52. A ball is released from rest at the left of...Ch. 7 - 53. The roller coaster ride starts from rest at...Ch. 7 - Prob. 54RCQ Ch. 7 - Prob. 55RCQ Ch. 7 - Why do you do no work on a 25-kg backpack when you...Ch. 7 - If your friend pushes a lawnmower four times as...Ch. 7 - Why does one get tired pushing against a...Ch. 7 - Prob. 59RCQ Ch. 7 - Prob. 60RCQ Ch. 7 - Prob. 61RCQ Ch. 7 - When a rifle with a longer barrel is fired, the...Ch. 7 - Prob. 63RCQ Ch. 7 - 64. You and a flight attendant toss a ball back...Ch. 7 - Prob. 65RCQ Ch. 7 - Prob. 66RCQ Ch. 7 - Prob. 67RCQ Ch. 7 - Prob. 68RCQ Ch. 7 - 69. A physics instructor demonstrates energy...Ch. 7 - Prob. 70RCQ Ch. 7 - Prob. 71RCQ Ch. 7 - 72. A moving hammer hits a nail and drives it into...Ch. 7 - Prob. 73RCQ Ch. 7 - 74. Why does the force of gravity do work on a car...Ch. 7 - Prob. 75RCQ Ch. 7 - Prob. 76RCQ Ch. 7 - Prob. 77RCQ Ch. 7 - Prob. 78RCQ Ch. 7 - Prob. 79RCQ Ch. 7 - Prob. 80RCQ Ch. 7 - Prob. 81RCQ Ch. 7 - Prob. 82RCQ Ch. 7 - Prob. 83RCQ Ch. 7 - Prob. 84RCQ Ch. 7 - Prob. 85RCQ Ch. 7 - When the velocity of an object is doubled, by what...Ch. 7 - Prob. 87RCQ Ch. 7 - Prob. 88RCQ Ch. 7 - Prob. 89RCQ Ch. 7 - If your momentum is zero, is your kinetic energy...Ch. 7 - 91. If two objects have equal kinetic energies, do...Ch. 7 - 92. Two lumps of clay with equal and opposite...Ch. 7 - Scissors for cutting paper have long blades and...Ch. 7 - Prob. 94RCQ Ch. 7 - Prob. 95RCQ Ch. 7 - Prob. 96RCQ Ch. 7 - Prob. 97RCQ Ch. 7 - Prob. 98RCQ Ch. 7 - Prob. 99RCQ Ch. 7 - 100. Consider the identical balls released from...Ch. 7 - Prob. 101RCQ Ch. 7 - Prob. 102RCQ Ch. 7 - Prob. 103RCQ Ch. 7 - Prob. 104RCQ Ch. 7 - Prob. 105RCQ Ch. 7 - Prob. 106RCQ Ch. 7 - Prob. 107RCQ Ch. 7 - Prob. 108RCQ Ch. 7 - 109. Your discussion partner is confused about...Ch. 7 - 110. In the absence of air resistance, a ball...Ch. 7 - 111. You’re on a rooftop and you throw one ball...Ch. 7 - 112. In the pulley system shown, block A has a...Ch. 7 - Prob. 113RCQ Ch. 7 - Prob. 114RCQ Ch. 7 - Prob. 115RCQ Ch. 7 - Prob. 116RCQ Ch. 7 - Prob. 117RCQ Ch. 7 - 118. Consider a bob attached by a string, a simple...Ch. 7 - Consider a satellite in a circular orbit above...Ch. 7 - 120. Consider the swinging-balls apparatus. If two...Ch. 7 - To combat wasteful habits, we often speak of...Ch. 7 - Prob. 122RCQ

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