Extended Response
12.2 First law of Thermodynamics: Thermal Energy and Work
Under which conditions will the work done by the gas in a system increase?
- It will increase when a large amount of energy is added to the system, and that energy causes an increase in the gas’s volume, its pressure, or both.
- It will increase when a large amount of energy is extracted from the system, and that energy causes an increase in the gas’s volume, its pressure, or both.
- It will increase when a large amount of energy is added to the system, and that energy causes a decrease in the gas’s volume, its pressure, or both.
- It will increase when a large amount of energy is extracted from the system, and that energy causes a decrease in the gas’s volume, its pressure, or both.
How does energy transfer by heat aid in body metabolism?
- The energy is given to the body through the work done by the body (W) and through the intake of food, which may also be considered as the work done on the body. The transfer of energy out of the body is by heat (−Q) .
- The energy given to the body is by the intake of food, which may also be considered as the work done on the body. The transfer of energy out of the body is by heat (−Q) and the work done by the body (W) .
- The energy given to the body is by the transfer of energy by heat (Q) into the body, which may also be considered as the work done on the body. The transfer of energy out of the body is the work done by the body (W) .
- The energy given to the body is by the transfer of energy by heat (Q) inside the body. The transfer of energy out of the body is by the intake of food and the work done by the body (W) .
Two distinct systems have the same amount of stored internal energy. Five hundred joules are added by heat to the first system, and 300 J are added by heat to the second system. What will be the change in internal energy of the first system if it does 200 J of work? How much work will the second system have to do in order to have the same internal energy?
- 700 J; 0 J
- 300 J; 300 J
- 700 J; 300 J
- 300 J; 0 J
12.4 Applications of Thermodynamics: Heat Engines, Heat Pumps, and Refrigerators
In the equation W = Qh − Qc, if the value of Qc were equal to zero, what would it signify?
- The efficiency of the engine is 75 percent.
- The efficiency of the engine is 25 percent.
- The efficiency of the engine is 0 percent.
- The efficiency of the engine is 100 percent.
A coal power station transfers 3.0×1012 J by heat from burning coal and transfers 1.5×1012 J by heat into the environment. What is the efficiency of the power station?
- 0.33
- 0.5
- 0.66
- 1