PHYSICS:F/SCI.+ENGRS-W/WEBASSIGN
10th Edition
ISBN: 9781337888479
Author: SERWAY
Publisher: CENGAGE L
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Textbook Question
Chapter 21, Problem 10P
An ideal refrigerator or ideal heat pump is equivalent to a Carnot engine running in reverse. That is, energy |Qc| is taken in from a cold reservoir and energy |Qh| is rejected to a hot reservoir. (a) Show that the work that must he supplied to run the refrigerator or heat pump is
(b) Show that the coefficient of performance (COP) of the ideal refrigerator is
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An object is subjected to a friction force with magnitude 5.49 N, which acts against the object's velocity. What is the work (in J) needed to move the object at constant speed for the following routes?
y (m)
C
B
(5.00, 5.00)
A
x (m)
©
(a) the purple path O to A followed by a return purple path to O
]
(b) the purple path O to C followed by a return blue path to O
]
(c) the blue path O to C followed by a return blue path to O
]
(d) Each of your three answers should be nonzero. What is the significance of this observation?
○ The force of friction is a conservative force.
○ The force of friction is a nonconservative force.
A block of mass m = 2.50 kg is pushed d = 2.30 m along a frictionless horizontal table by a constant applied force of magnitude F = 10.0 N directed at an angle
25.0° below the horizontal as shown in the figure below.
m
(a) Determine the work done by the applied force.
]
(b) Determine the work done by the normal force exerted by the table.
]
(c) Determine the work done by the force of gravity.
]
(d) Determine the work done by the net force on the block.
]
A man pushing a crate of mass m = 92.0 kg at a speed of v = 0.845 m/s encounters a rough horizontal surface of length = 0.65 m as in the figure below. If the coefficient of kinetic friction between the crate and rough surface is 0.357 and he exerts a constant horizontal force of 294 N on
the crate.
e
(a) Find the magnitude and direction of the net force on the crate while it is on the rough surface.
magnitude
direction
---Select---
N
(b) Find the net work done on the crate while it is on the rough surface.
]
(c) Find the speed of the crate when it reaches the end of the rough surface.
m/s
Chapter 21 Solutions
PHYSICS:F/SCI.+ENGRS-W/WEBASSIGN
Ch. 21.1 - The energy input to an engine is 4.00 times...Ch. 21.2 - The energy entering an electric heater by...Ch. 21.4 - Three engines operate between reservoirs separated...Ch. 21.6 - (a) Suppose you select four cards at random from a...Ch. 21.7 - An ideal gas is taken from an initial temperature...Ch. 21.7 - True or False: The entropy change in an adiabatic...Ch. 21 - A particular heat engine has a mechanical power...Ch. 21 - The work done by an engine equals one-fourth the...Ch. 21 - Suppose a heat engine is connected to two energy...Ch. 21 - During each cycle, a refrigerator ejects 625 kJ of...
Ch. 21 - A freezer has a coefficient of performance of...Ch. 21 - A heat pump has a coefficient of performance equal...Ch. 21 - One of the most efficient heat engines ever built...Ch. 21 - Why is the following situation impossible? An...Ch. 21 - If a 35.0% -efficient Carnot heat engine (Fig....Ch. 21 - An ideal refrigerator or ideal heat pump is...Ch. 21 - A heat engine is being designed to have a Carnot...Ch. 21 - A power plant operates at a 32.0% efficiency...Ch. 21 - You are working on a summer job at a company that...Ch. 21 - A Carnot heat engine operates between temperatures...Ch. 21 - An electric generating station is designed to have...Ch. 21 - Suppose you build a two-engine device with the...Ch. 21 - A heat pump used for heating shown in Figure...Ch. 21 - A gasoline engine has a compression ratio of 6.00....Ch. 21 - An idealized diesel engine operates in a cycle...Ch. 21 - (a) Prepare a table like Table 21.1 for the...Ch. 21 - Prob. 21PCh. 21 - A Styrofoam cup holding 125 g of hot water at 100C...Ch. 21 - A 1 500-kg car is moving at 20.0 m/s. The driver...Ch. 21 - A 2.00-L container has a center partition that...Ch. 21 - Calculate the change in entropy of 250 g of water...Ch. 21 - What change in entropy occurs when a 27.9-g ice...Ch. 21 - When an aluminum bar is connected between a hot...Ch. 21 - When a metal bar is connected between a hot...Ch. 21 - How fast are you personally making the entropy of...Ch. 21 - Prob. 30APCh. 21 - The energy absorbed by an engine is three times...Ch. 21 - In 1993, the U.S. government instituted a...Ch. 21 - In 1816, Robert Stirling, a Scottish clergyman,...Ch. 21 - Suppose an ideal (Carnot) heat pump could be...Ch. 21 - Review. This problem complements Problem 44 in...Ch. 21 - A firebox is at 750 K, and the ambient temperature...Ch. 21 - A 1.00-mol sample of an ideal monatomic gas is...Ch. 21 - A system consisting of n moles of an ideal gas...Ch. 21 - A heat engine operates between two reservoirs at...Ch. 21 - You are working as an assistant to a physics...Ch. 21 - Prob. 41APCh. 21 - You are working as an expert witness for an...Ch. 21 - An athlete whose mass is 70.0 kg drinks 16.0...Ch. 21 - Prob. 44APCh. 21 - Prob. 45APCh. 21 - A sample consisting of n moles of an ideal gas...Ch. 21 - The compression ratio of an Otto cycle as shown in...
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