Essential University Physics (3rd Edition)
3rd Edition
ISBN: 9780134202709
Author: Richard Wolfson
Publisher: PEARSON
expand_more
expand_more
format_list_bulleted
Concept explainers
Question
Chapter 19, Problem 9FTD
To determine
To explain: Why refrigerators and heat pumps have different
Expert Solution & Answer
Want to see the full answer?
Check out a sample textbook solutionStudents have asked these similar questions
Explain why heat pumps do not work as well in very cold climates as they do in milder ones. Is the same true of refrigerators?
A heat engine running backward is called a refrigerator if its
purpose is to extract heat from a cold reservoir. The same
engine running backward is called a heat pump if its
purpose is to exhaust warm air into the hot reservoir. Heat
pumps are widely used for home heating. You can think of
a heat pump as a refrigerator that is cooling the already
cold outdoors and, with its exhaust heat QH, warming the
indoors. Perhaps this seems a little silly, but consider the
following. Electricity can be directly used to heat a home by
passing an electric current through a heating coil. This is a
direct, 100% conversion of work to heat. That is, 19.0 kW
of electric power (generated by doing work at the rate
19.0 kJ/s at the power plant) produces heat energy inside
the home at a rate of 19.0 kJ/s. Suppose that the
neighbor's home has a heat pump with a coefficient of
performance of 3.00, a realistic value. NOTE: With a
refrigerator, "what you get" is heat removed. But with a
heat pump, "what you…
The second law of thermodynamics states that we cannot build a perfect heat engine. Explain why.
Chapter 19 Solutions
Essential University Physics (3rd Edition)
Ch. 19.1 - Which of these processes is irreversible? (a)...Ch. 19.2 - The low temperature for a practical heat engine is...Ch. 19.3 - A clever engineer decides to increase the...Ch. 19.4 - In each of the following processes, does the...Ch. 19 - Could you cool the kitchen by leaving the...Ch. 19 - Prob. 2FTDCh. 19 - Should a car get better mileage in the summer or...Ch. 19 - Prob. 4FTDCh. 19 - Name some irreversible processes that occur in a...Ch. 19 - Your power company claims that electric heat is...
Ch. 19 - A hydroelectric power plant, using the energy of...Ch. 19 - A heat-pump manufacturer claims the device will...Ch. 19 - Prob. 9FTDCh. 19 - The heat Q added during adiabatic free expansion...Ch. 19 - Energy is conserved, so why cant we recycle it as...Ch. 19 - Why doesnt the evolution of human civilization...Ch. 19 - What are the efficiencies of reversible heat...Ch. 19 - A cosmic heat engine might operate between the...Ch. 19 - A reversible Carnot engine operating between...Ch. 19 - A Carnot engine absorbs 900 J of heat each cycle...Ch. 19 - Find the COP of a reversible refrigerator...Ch. 19 - Prob. 18ECh. 19 - The human body can be 25% efficient at converting...Ch. 19 - Calculate the entropy change associated with...Ch. 19 - You metabolize a 650-kcal burger at your 37C body...Ch. 19 - You heat 250 g of water from 10C to 95C. By how...Ch. 19 - Melting a block of lead already at its melting...Ch. 19 - How much energy becomes unavailable for work in an...Ch. 19 - Prob. 25ECh. 19 - A Carnot engine extracts 745 J from a 592-K...Ch. 19 - The maximum steam temperature in a nuclear power...Ch. 19 - Youre engineering an energy-efficient house that...Ch. 19 - A power plants electrical output is 750 MW....Ch. 19 - A power plant extracts energy from steam at 280C...Ch. 19 - The electric power output of all the thermal...Ch. 19 - Consider a Carnot engine operating between...Ch. 19 - An industrial freezer operates between 0C and 32C,...Ch. 19 - Use appropriate energy-flow diagrams to analyze...Ch. 19 - Prob. 35PCh. 19 - A refrigerator maintains an interior temperature...Ch. 19 - You operate a store thats heated by an oil furnace...Ch. 19 - Use energy-flow diagrams to show that the...Ch. 19 - A heat pump extracts energy from groundwater at...Ch. 19 - A reversible engine contains 0.350 mol of ideal...Ch. 19 - (a) Determine the efficiency for the cycle shown...Ch. 19 - A 0.20-mol sample of an ideal gas goes through the...Ch. 19 - A shallow pond contains 94 Mg of water. In winter,...Ch. 19 - Estimate the rate of entropy increase associated...Ch. 19 - The temperature of n moles of ideal gas is changed...Ch. 19 - The temperature of n moles of ideal gas is changed...Ch. 19 - A 6.36-mol sample of ideal diatomic gas is at 1.00...Ch. 19 - A 250-g sample of water at 80C is mixed with 250 g...Ch. 19 - An ideal gas undergoes a process that takes it...Ch. 19 - In an adiabatic free expansion, 6.36 mol of ideal...Ch. 19 - Find the entropy change when a 2.4-kg aluminum pan...Ch. 19 - An engine with mechanical power output 8.5 kW...Ch. 19 - Find the change in entropy as 2.00 kg of H2O at...Ch. 19 - Gasoline engines operate approximately on the Otto...Ch. 19 - The compression ratio r of an engine is the ratio...Ch. 19 - In a diesel cycle, gas at volume V1 and pressure...Ch. 19 - (a) Show that the heal flowing into the diesel...Ch. 19 - Youre considering buying a car that comes in...Ch. 19 - The 54-M W wood-fired McNeil Generating Station in...Ch. 19 - A 500-g copper block at 80C is dropped into 1.0 kg...Ch. 19 - An objects heat capacity is inversely proportional...Ch. 19 - A Carnot engine extracts heat from a block of mass...Ch. 19 - In an alternative universe, youve got the...Ch. 19 - Youre the environmental protection officer for a...Ch. 19 - Find an expression for the entropy gain when hot...Ch. 19 - Problem 74 of Chapter 16 provided an approximate...Ch. 19 - The molar specific heat at constant pressure for a...Ch. 19 - Prob. 68PCh. 19 - Energy-efficiency specialists measure the heat Qh...Ch. 19 - Refrigerators remain among the greatest consumers...Ch. 19 - The refrigerators COP is a. 13. b. 2. c. 3. d. 4.Ch. 19 - The fuel energy consumed at the power plant to run...Ch. 19 - Prob. 73PP
Knowledge Booster
Learn more about
Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, physics and related others by exploring similar questions and additional content below.Similar questions
- Show that the coefficients of performance of refrigerators and heat pumps are related by COPref=COPhp1. Start with the definitions of the COP s and the conservation of energy relationship between Qh, QC, and W.arrow_forwardA hot rock ejected from a volcano's lava fountain cools from 250°C to 95.0°C, and its entropy decreases by 350 J/K. How much heat transfer (in J) occurs from the rock?arrow_forwardIf energy is always conserved, never created or destroyed, then why do most of the machines in our lives eventually stop working and have to be replaced? Explain using concepts from the textbook. The chapters and topics based on these questions come from these concepts. (Phase Changes Thermodynamics.)arrow_forward
- Consider two actual power plants operating with solar energy. Energy is supplied to one plant from a solar pond at 80°C and to the other from concentrating collectors that raise the water temperature to 600°C. Which of these power plants will have a higher efficiency? Explain.arrow_forward(h) Figure Ql.(h) below shows the emission of steam from a kettle causing a pinwheel to turn. Which of the laws of thermodynamics best explains this phenomenon? Justify your answer. Figure Q1.(h)arrow_forwardEnergy transfers take place constantly in everyday activities. Think of two scenarios: cooking on a stove and driving. Explain how the second law of thermodynamics applies to these two scenarios.arrow_forward
- A refrigerator moves heat from cold to warm. Why does this not violate the second law of thermodynamics?arrow_forwardHow much kinetic energy would I have to generate by rubbing my hands together to light my hands on fire? Utilize an equation that relates to thermodynamics to answer this question.arrow_forwardAn engineer designs a heat engine using flat-plate solar collectors. The collectors deliver heat at 74°C and the engine releases heat to the surroundings at 32°C. What is the maximum possible efficiency of this engine? (Round the final answer to four decimal places.) The maximum efficiency of the engine is __%arrow_forward
- How can we apply the first law of thermodynamics to heat engines, heatpumps, and refrigerators?arrow_forwardWhat is the basic idea behind a refrigerator? It sucks in cold air from the room and pumps it into the food compartment. It makes cold air and injects it into the food compartment. It removes heat from the compartment and pumps it to the outside.arrow_forwardWhy is it incorrect to say that the refrigerator door must be kept close because coldness (or cold air) might escape in terms of thermodynamics? Explain why is the phrase incorrect in layman's terms.arrow_forward
arrow_back_ios
SEE MORE QUESTIONS
arrow_forward_ios
Recommended textbooks for you
- College PhysicsPhysicsISBN:9781938168000Author:Paul Peter Urone, Roger HinrichsPublisher:OpenStax CollegePrinciples of Physics: A Calculus-Based TextPhysicsISBN:9781133104261Author:Raymond A. Serway, John W. JewettPublisher:Cengage Learning
College Physics
Physics
ISBN:9781938168000
Author:Paul Peter Urone, Roger Hinrichs
Publisher:OpenStax College
Principles of Physics: A Calculus-Based Text
Physics
ISBN:9781133104261
Author:Raymond A. Serway, John W. Jewett
Publisher:Cengage Learning