Heat and Thermodynamics - SS2 Physics Past Questions and Answers - page 4
The efficiency of a heat engine is given by:
The input heat divided by the output work.
The output heat divided by the input work.
The input work is divided by the output heat.
The output work is divided by the input heat.
The Carnot cycle is an idealised thermodynamic cycle that consists of:
Two isothermal and two adiabatic processes.
Two isothermal and two isochoric processes.
Two isochoric and two adiabatic processes.
Two isochoric and two isobaric processes.
The third law of thermodynamics states that:
It is impossible to reach absolute zero temperature.
The entropy of a perfect crystal at absolute zero is zero.
Energy is conserved in all thermodynamic processes.
Heat cannot be completely converted into work.
A heat engine takes in 2000 J of heat from a high-temperature reservoir and produces 800 J of work. How much heat is rejected to the low-temperature reservoir?
A refrigerator operates between two reservoirs at temperatures of 5°C and 25°C. The refrigerator removes 500 J of heat from the cold reservoir. How much work is required for this process?
A heat engine has an efficiency of 50% and takes in 1000 J of heat. How much work does the engine produce?
In a refrigeration system, which component is responsible for changing the refrigerant from a high-pressure gas to a high-pressure liquid?
Compressor
Condenser
Expansion valve
Evaporator
Which of the following statements is true about the coefficient of performance (COP) of a refrigerator or heat pump?
The COP of a refrigerator is always greater than the COP of a heat pump.
The COP of a heat pump is always greater than the COP of a refrigerator.
The COP of a refrigerator and a heat pump are always equal.
The COP of a refrigerator and a heat pump depends on the temperature difference between the reservoirs.
In a heat pump, which component is responsible for absorbing heat from the external environment and transferring it to the indoor space?
Compressor
Condenser
Expansion valve
Evaporator
Which of the following statements is true about the Carnot refrigeration cycle?
It operates between two temperature reservoirs and has the highest possible efficiency.
It operates between two temperature reservoirs and has the lowest possible efficiency.
It operates between multiple temperature reservoirs and has the highest possible efficiency.
It operates between multiple temperature reservoirs and has the lowest possible efficiency.