Conceptual Physics (12th Edition)
12th Edition
ISBN: 9780321909107
Author: Paul G. Hewitt
Publisher: PEARSON
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Textbook Question
Chapter 7, Problem 6RCQ
If both sacks in the preceding question are lifted their respective distances in the same time, how does the power required for each compare? How about for the case in which the lighter sack is moved its distance in half the time?
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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. 4RCQCh. 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. 17RCQCh. 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. 22RCQCh. 7 - Prob. 23RCQCh. 7 - Prob. 24RCQCh. 7 - 25. Can we correctly say that hydrogen is a new...Ch. 7 - Prob. 26RCQCh. 7 - Prob. 27RCQCh. 7 - Prob. 28RCQCh. 7 - Prob. 29RCQCh. 7 - Prob. 30RCQCh. 7 - Prob. 31RCQCh. 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. 34RCQCh. 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. 40RCQCh. 7 - Prob. 41RCQCh. 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. 54RCQCh. 7 - Prob. 55RCQCh. 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. 59RCQCh. 7 - Prob. 60RCQCh. 7 - Prob. 61RCQCh. 7 - When a rifle with a longer barrel is fired, the...Ch. 7 - Prob. 63RCQCh. 7 - 64. You and a flight attendant toss a ball back...Ch. 7 - Prob. 65RCQCh. 7 - Prob. 66RCQCh. 7 - Prob. 67RCQCh. 7 - Prob. 68RCQCh. 7 - 69. A physics instructor demonstrates energy...Ch. 7 - Prob. 70RCQCh. 7 - Prob. 71RCQCh. 7 - 72. A moving hammer hits a nail and drives it into...Ch. 7 - Prob. 73RCQCh. 7 - 74. Why does the force of gravity do work on a car...Ch. 7 - Prob. 75RCQCh. 7 - Prob. 76RCQCh. 7 - Prob. 77RCQCh. 7 - Prob. 78RCQCh. 7 - Prob. 79RCQCh. 7 - Prob. 80RCQCh. 7 - Prob. 81RCQCh. 7 - Prob. 82RCQCh. 7 - Prob. 83RCQCh. 7 - Prob. 84RCQCh. 7 - Prob. 85RCQCh. 7 - When the velocity of an object is doubled, by what...Ch. 7 - Prob. 87RCQCh. 7 - Prob. 88RCQCh. 7 - Prob. 89RCQCh. 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. 94RCQCh. 7 - Prob. 95RCQCh. 7 - Prob. 96RCQCh. 7 - Prob. 97RCQCh. 7 - Prob. 98RCQCh. 7 - Prob. 99RCQCh. 7 - 100. Consider the identical balls released from...Ch. 7 - Prob. 101RCQCh. 7 - Prob. 102RCQCh. 7 - Prob. 103RCQCh. 7 - Prob. 104RCQCh. 7 - Prob. 105RCQCh. 7 - Prob. 106RCQCh. 7 - Prob. 107RCQCh. 7 - Prob. 108RCQCh. 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. 113RCQCh. 7 - Prob. 114RCQCh. 7 - Prob. 115RCQCh. 7 - Prob. 116RCQCh. 7 - Prob. 117RCQCh. 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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- Check Your Understanding There is a second solution to the system of equations solved in this example (because the energy equation is quadratic): v1.f=-2.5m/s , v2.f=0 . This solution is unacceptable on physical grounds; what’s with it?arrow_forwardCheck Your Understanding (a) A car and a truck each moving with the same kinetic energy. Assume that the truck has more mass than the car. Which has the greater speed? (b) A car truck are each moving with same speed. Which has the greater kinetic energy?arrow_forwardIn a common physics demonstration, a bowling ball is suspended from the ceiling by a rope. The professor pulls the ball away from its equilibrium position and holds it adjacent to his nose, as shown below. He releases the ball so that it swings directly away from him. Does he get struck by the ball on its return swing? What is he trying to show in this demonstration?arrow_forward
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