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Conceptual Physics / MasteringPhysics (Book & Access Card)
12th Edition
ISBN: 9780321908605
Author: Paul G. Hewitt
Publisher: PEARSON
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Textbook Question
Chapter 7, Problem 8RCQ
Two cars are raised to the same elevation on service- station lifts. If one car is twice as massive as the other, compare their gains of potential energy.
Expert Solution & Answer
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In the figures, the masses are hung from an elevator ceiling. Assume the velocity of the elevator is constant. Find the tensions in
the ropes (in N) for each case. Note that 0₁ = 35.0°, 0₂ = 55.0°, 03 = 60.0°, m₁ = 3.00 kg, and m2 = 7.00 kg. (Due to the
nature of this problem, do not use rounded intermediate values-including answers submitted in WebAssign-in your calculations.)
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(b)
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You are working with a movie director and investigating a scene with a cowboy sliding off a tree limb and falling onto the saddle of
a moving horse. The distance of the fall is several meters, and the calculation shows a high probability of injury to the cowboy
from the stunt. Let's look at a simpler situation. Suppose the director asks you to have the cowboy step off a platform 2.55 m off
the ground and land on his feet on the ground. The cowboy keeps his legs straight as he falls, but then bends at the knees as
soon as he touches the ground. This allows the center of mass of his body to move through a distance of 0.660 m before his body
comes to rest. (Center of mass will be formally defined in Linear Momentum and Collisions.) You assume this motion to be under
constant acceleration of the center of mass of his body. To assess the degree of danger to the cowboy in this stunt, you wish to
calculate the average force upward on his body from the ground, as a multiple of the cowboy's…
A box of mass m = 2.00 kg is released from rest at the top of an inclined plane as seen in the figure. The box starts out at height
h =0.200 m above the top of the table, the table height is H = 2.00 m, and 0 = 41.0°.
H
m
(a) What is the acceleration (in m/s²) of the box while it slides down the incline?
m/s²
(b) What is the speed (in m/s) of the box when it leaves the incline?
m/s
(c) At what horizontal distance (in m) from the end of the table will the box hit the ground?
m
(d) How long (in s) from when the box is released does it hit the ground?
S
(e) Does the box's mass affect any of your above answers?
Yes
No
Chapter 7 Solutions
Conceptual Physics / MasteringPhysics (Book & Access Card)
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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