"The Efficiency of Heat Engines" Utilization of Internal Energy PPT

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"The Efficiency of Heat Engines" Utilization of Internal Energy PPT

Part One Content: Basic Knowledge Key Points

Knowledge point 1: Calorific value of fuel

1. At 22:07 on September 19, 2018, my country successfully launched the 37th and 38th Beidou navigation satellites using the "Long March 3B" carrier rocket at the Xichang Satellite Launch Center in a "one rocket and two stars" method. The launch vehicle uses liquid hydrogen as fuel mainly because of its high calorific value.

2. (Zhuzhou High School Entrance Examination) The calorific value of charcoal is 3.4×107 J/kg, which means 1 kg of charcoal (D)

A. Has a heat of 3.4×107 J

B. Has an internal energy of 3.4×107 J

C. The external work done by complete combustion is 3.4×107 J

D. Complete combustion releases heat 3.4×107 J

3. Regarding the calorific value of fuel, which of the following statements is correct (C)

A. The calorific value of the fuel is directly proportional to the heat released when the fuel is burned.

B. Fuel has no calorific value when it is not burned.

C. For a certain fuel, its calorific value is a certain value, which has nothing to do with the quality of the fuel and the heat released by the combustion of the fuel.

D. The calorific value of fuel that burns easily must be large.

Knowledge point 2: The efficiency of heat engines

4. With the development of economy, cars have entered the homes of ordinary people. When people choose a car, the efficiency of the engine (gasoline engine) is one of the important indicators to distinguish the quality of the car. Experienced drivers can make a rough judgment by testing the temperature of the car's exhaust with their hands. When the output power is the same, the lower the exhaust gas temperature, the higher the efficiency of the automobile engine (optional "high" or "low").

5. Regarding the efficiency of heat engines, which of the following statements is correct (D)

A. The efficiency of steam engines is usually higher than that of gasoline engines

B. Some new fuel vehicles have achieved zero emissions and their efficiency has reached 100%

C. Heat engine efficiency is not necessarily less than 100%

D. Even on a frictionless road, the efficiency of a car engine cannot reach 100%

6. The figure shows the energy flow diagram of an internal combustion engine. The heat engine efficiency of the internal combustion engine is (B)

A.25% B.35% C.40% D.75%

PPT on the efficiency of heat engines, part 2: improvement of comprehensive capabilities

7. There are two identical devices as shown in the figure. Different fuels with the same mass are put into the two burning dishes respectively. After igniting, the same liquid with the same mass is heated. By comparing the fuels, all the fuels are burned (optional "same burning time" or "all burned") to determine the calorific value of the two fuels. Using a liquid with a smaller specific heat capacity can make the experimental phenomenon more obvious (the liquid did not boil during the experiment).

8. As shown in the figure is the energy flow diagram of an internal combustion engine, the efficiency of the internal combustion engine can be expressed as η= E_2/E　×100% (expressed by letters).

9. (Heilongjiang High School Entrance Examination) When an adult participates in a long-distance run, the energy consumed by the body is 6.6×106 J. This energy is equivalent to the complete burning of 0.55 kg of dry firewood. The calorific value of dry firewood is 1.2×107 J/kg. ;After half of the dry wood is used, the calorific value of the remaining dry wood will remain unchanged (select "increase", "decrease" or "unchange").

10. Thousands of sails are racing, hundreds of boats are racing against each other. In the context of today's rapid changes in energy science and technology, combustible ice is a clean energy source with great potential. my country plans to conquer the key technologies for trial production of natural gas hydrate in sea areas by 2020 and achieve commercial trial production. Under the same conditions, the heat released by complete combustion of combustible ice can reach dozens of times that of gas, indicating that the calorific value of combustible ice is very large. Calculated based on the 10 times relationship, the heat released by the complete combustion of 500 g of flammable ice is 2.1×108 J. This heat can heat 625kg of water from 20 ℃ to 100 ℃. c water = 4.2×103 J/( kg ·℃), qgas=4.2×107 J/kg].

11. After a third-grade student in a school visited the school’s boiler room, he put forward the following suggestions to improve the efficiency of the furnace. Among them, the one that should not be adopted is (B)

A. The blower blows air into the furnace to blow up the coal particles and burn them.

B. Add more coal to the furnace to increase the firepower

C. Grind coal into powder and blow it into the furnace with air

D. Use various methods to increase the heating area

12. (Xining High School Entrance Examination) As the old saying goes: "People must be solid, and fire must be weak." The meaning of this saying is that a person must be down-to-earth in order to have a successful career; combustibles must be elevated in order to burn more vigorously. The purpose of "fire must be weak" is (D)

A. Increase the calorific value of combustibles B. Reduce the ignition point of combustibles

C. Complete combustion of combustibles D. Improve the utilization rate of combustibles

13. The picture shows the experimental device for "exploring the calorific value of alcohol, kerosene, and gasoline." The devices A, B, and C are exactly the same, and the mass and initial temperature of the water in the beaker and the mass of the fuel to be measured are also the same. By measuring the final temperature of water after all fuels are fully burned (none has reached the boiling point) t A < t B = t C, we can roughly know that the relationship between their calorific values ​​q is (D)

A.qAqB=qC

C.qA>qB>qC D.qA

The efficiency of heat engines PPT, the third part of the content: Expansion of research and breakthroughs

18. The figure is a schematic diagram of a certain cylinder four-stroke diesel engine. The rotation speed of the diesel engine is 600 r/min, and the cross-sectional area of ​​the piston is 120 cm2. During the power stroke, the average pressure of the gas on the piston is 5×105 Pa, and the distance the piston moves is 30 cm. beg:

(1) The average pressure of gas on the piston during the power stroke;

(2) The power of average pressure during the power stroke;

(3) Assuming that the gasoline is completely burned during the power stroke and the heat released is 6×103 J, what is the efficiency of the diesel engine?

Keywords: Free download of PPT courseware for ninth-grade physics from the People's Education Press, PPT download on the efficiency of heat engines, PPT download on the utilization of internal energy, .PPT format;

For more information about the PPT courseware "Utilization of Internal Energy and the Efficiency of Heat Engines", please click on the Utilization of Internal Energy ppt Efficiency of Heat Engines ppt tag.

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Update Time: 2024-11-03

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