Energy and the First Law of Thermodynamics

1. In thermodynamics, the correct sign convention is:

• 1. W>0 means work done on the system

• Q > 0 means heat transferred from the system

• W > 0 means work done by the system

• Q < 0 means heat transferred to the system

Which statement about heat is correct?

• Heat is a property stored inside a system

• Heat is an energy transfer driven only by a temperature difference

• Heat always equals work in any process

• Heat is defined only in conduction

The thermal efficiency of a power cycle is:

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The coefficient of performance (COP) of a refrigeration cycle is:

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Which expression correctly represents the energy balance for a closed system?

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Determine the change in kinetic energy in [kJ].

Answer explanation

Determine the change in potential energy, in kJ.

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Determine the work done during the expansion in [kJ].

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Determine the heat transfer Q in [kJ]

Answer explanation

Determine the net work output in [kJ]?

Answer explanation