The surface waters of tropical oceans are at a temperature of 27°C while water at a depth of 1200 m is at 3°C. It has been suggested these warm and cold waters could be the energy reservoirs for a
Want to see the full answer?
Check out a sample textbook solutionChapter 11 Solutions
College Physics: A Strategic Approach (3rd Edition)
Additional Science Textbook Solutions
Essential University Physics: Volume 1 (3rd Edition)
Tutorials in Introductory Physics
The Cosmic Perspective (8th Edition)
Physics for Scientists and Engineers: A Strategic Approach, Vol. 1 (Chs 1-21) (4th Edition)
Physics for Scientists and Engineers: A Strategic Approach with Modern Physics (4th Edition)
Essential University Physics (3rd Edition)
- A thermal engine produces 4 MJ of electrical energy while operating between two thermal baths of different temperatures. The working substance of the engine discharges 5 MJ of heat to the cold temperature bath. What is the efficiency of the engine?arrow_forwardWater falls over a dam of height h with a mass flow rate of R, in units of kilograms per second. (a) Show that the power available from the water is P=Rgh where g is the free-fall acceleration. (b) Each hydroelectric unit at the Grand Coulee Dam takes in water at a rate of 8.50 105 kg/s from a height of 87.0 m. The power developed by the falling water is converted to electric power with an efficiency of 85.0%. How much electric power does each hydroelectric unit produce?arrow_forwardShow 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_forward
- (a) On a winter day, a certain house loses 5.00108J of heat to the outside (about 500,000 Btu). What is the total change in entropy due to this heat transfer alone, assuming an average indoor temperature of 21.0C and an average outdoor temperature of 5.00C ? (b) This large change in entropy implies a large amount of energy has become unavailable to do work. Where do we find more energy when such energy is lost to us?arrow_forward(a) What is the hot reservoir temperature of a Carnot engine that has an eficiency of 42.0% and a cold reservoir temperature of 210C ? (b) What must the hot reservoir temperature be for a real heat engine that achieves 0.700 of the maximum eficiency, but still has an efficiency of 42.0% (and a cold reservoir at 27.0C )? (c) Does your answer imply practical limits to the efficiency of car gasoline engines?arrow_forwardA power plant has been proposed that would make use of the temperature gradient in the ocean. The system is to operate between 20.0C (surface water temperature) and 5.00C (water temperature at a depth of about 1 km). (a) What is the maximum efficiency of such a system? (b) If the useful power output of the plant is 75.0 MW, how much energy is absorbed per hour? (c) In view of your answer to part (a), do you think such a system is worthwhile (considering that there is no charge for fuel)?arrow_forward
- Of the following, which is not a statement of the second law of thermodynamics? (a) No heat engine operating in a cycle can absorb energy from a reservoir and use it entirely to do work, (b) No real engine operating between two energy reservoirs can be more efficient than a Carnot engine operating between the same two reservoirs, (c) When a system undergoes a change in state, the change in the internal energy of the system is the sum of the energy transferred to the system by heat and the work done on the system, (d) The entropy of the Universe increases in all natural processes, (e) Energy will not spontaneously transfer by heat from a cold object to a hot object.arrow_forward(a) What is the best coefficient of performance for a refrigerator that cools an environment at 30.0C and has heat transfer to another environment at 45.0C ? (b) How much work in joules must be done for a heat transfer of 4186 kJ from the cold environment? (c) What is the cost of doing this if the work costs 10.0 cents per 3.60106J (a kilowatthour)? (d) How many kJ of heat transfer occurs into the warm environment? (e) Discuss what type of refrigerator might operate between these temperatures.arrow_forwardIceland has both high geothermal activity, with high temperatures near the surface, and abundant cold surface water. Iceland has many power plants that take advantage of the proximity of these natural hot and cold reservoirs. One plant uses an underground source at 122°C as the hot reservoir and a nearby lake at 5°C as the cold reservoir. The plant draws 16 MW from the hot reservoir to produce 1.8 MW of electricity. How does the actual efficiency ofthe plant compare to the theoretical maximum efficiency?arrow_forward
- As a gasoline engine is running, the amount of gasoline containing 15,000J of chemical potential energy is burned in 1 s. During that second, the engine does 3,000J of work. The burning gasoline has a temperature of about 2500 K. The waste heat from the engine flows into the air at about 300 K. What is the Carnot efficiency of a heat engine operating between these two temperatures?arrow_forwardA 1600 kg car steadily accelerates from rest to 60 mi/hr over a 2.8 second time span. How much work is done on the car. The car's mechanical efficiency is 0.20. As the car drives, it gets hotter and it also heats up its environment. If we make the (overly simplistic) assumption that the half of the thermal energy goes out to the wider environment while the car is speeding up, Hint: You can use the mechanical efficiency to find the overall chemical energy used. Using what you found in the previous problem, you can find the total thermal energy produced and from that, plus the assumption about how that energy is distributed, you can calculate the heat transfer. what is the heat transfer from the car to the environment?arrow_forwardA typical temperature for surface water in a tropical ocean is 27°C. Whereas at a depth of a kilometer or more it is only about 27°C whereas at a depth of a kilometer or more it is only about 5°C. It has been proposed to operate heat engines using surface water as the hot reservoir and deep water as the cold reservoir. What would the maximum efficiency of such an engine be? Why might such engine eventually be practical proposition even with so low an efficiency?arrow_forward
- Physics for Scientists and Engineers: Foundations...PhysicsISBN:9781133939146Author:Katz, Debora M.Publisher:Cengage LearningPrinciples of Physics: A Calculus-Based TextPhysicsISBN:9781133104261Author:Raymond A. Serway, John W. JewettPublisher:Cengage LearningCollege PhysicsPhysicsISBN:9781938168000Author:Paul Peter Urone, Roger HinrichsPublisher:OpenStax College
- Physics for Scientists and EngineersPhysicsISBN:9781337553278Author:Raymond A. Serway, John W. JewettPublisher:Cengage LearningPhysics for Scientists and Engineers with Modern ...PhysicsISBN:9781337553292Author:Raymond A. Serway, John W. JewettPublisher:Cengage Learning