Free Practice Quiz Question List

6 Thermodynamic Cycles Online Quiz Questions

Use this free practice quiz with 20 questions to review 6 Thermodynamic Cycles, test your knowledge, and prepare for your next test or exam.

20 questions

True or false

1 point

A working substance completes a thermodynamic cycle and returns to its initial state. Its net change in internal energy over the cycle is zero.

A
True
B
False

Choose one

1 point

On a pressure–volume diagram, what does a clockwise cycle loop generally indicate?

A
It indicates net work input to the working fluid.
B
It generally indicates positive net work done by the working fluid.
C
It indicates that the cycle has zero net boundary work.
D
It shows that the working fluid’s internal energy increases over the complete cycle.

Fill in the blank

1 point

For a complete cycle, $\Delta U=0$ . With heat entering and work done by the system positive, $Q_{\text{net}}=$ . Enter the symbol for net work.

Choose one

1 point

In a Rankine cycle, what is the pump’s main function?

A
It rejects heat and turns the working fluid into liquid.
B
It expands steam to produce work.
C
It raises the pressure of the liquid.
D
It adds heat to convert the liquid into steam.

Choose all

1 point

Select all statements that accurately describe the use of a temperature–entropy diagram.

A
For an internally reversible process, the area under a path represents heat transfer.
B
The area enclosed by a T–s cycle always gives the net boundary work.
C
A diagram alone may not provide enough information to calculate cycle performance.
D
The area under any path represents heat transfer, whether or not the process is internally reversible.

True or false

1 point

A power cycle operating between hot and cold surroundings can convert all of its supplied heat into net work if its components are perfectly reversible.

A
True
B
False

Written response

1 point

A power cycle receives $1200\ \text{kJ}$ of heat and rejects $780\ \text{kJ}$ . What is its thermal efficiency? Enter the percentage value without the percent sign.

Fill in the blank

1 point

Complete the refrigerator coefficient-of-performance formula by entering the symbol for heat absorbed from the cold space: $\mathrm{COP}_{\text{refrigerator}}=\frac{$ $}{W_{\text{in}}}$ .

Choose all

1 point

In a common vapor-compression cycle, select all accurate descriptions of component functions.

A
The compressor requires work input.
B
The condenser releases heat to the warm surroundings.
C
The evaporator absorbs heat from the cooled space.
D
The expansion device supplies the cycle’s net work output.

Written response

1 point

In a steady-flow device, which component typically produces work as the fluid’s enthalpy decreases?

Open ended

1 point

Explain why a cycle diagram may help you understand a thermodynamic cycle but still be insufficient by itself to calculate the cycle’s performance.

Choose one

1 point

Which energy-balance equation relates the heat delivered to the warm surroundings, the heat absorbed from the cold space, and work input for a refrigerator or heat pump?

A
$Q_{\text{out}}=Q_{\text{in}}-W_{\text{in}}$
B
$Q_{\text{out}}=Q_{\text{in}}+W_{\text{in}}$
C
$Q_{\text{in}}=Q_{\text{out}}+W_{\text{in}}$
D
$W_{\text{in}}=Q_{\text{out}}+Q_{\text{in}}$

Written response

1 point

A heat pump absorbs $360\ \text{kJ}$ from a cold space and uses $90\ \text{kJ}$ of work. What is its coefficient of performance? Enter a number.

Choose one

1 point

How does the performance of real Rankine-cycle devices compare with ideal predictions?

A
Actual work output and efficiency are below ideal predictions.
B
Actual work output is higher because real devices are irreversible.
C
Irreversibility makes the cycle’s net change in internal energy nonzero.
D
Actual efficiency equals the ideal prediction because the fluid returns to its initial state.

True or false

1 point

True or false: Because a thermodynamic cycle returns its working substance to its initial state, the net change in the substance's internal energy over the cycle is zero.

A
True
B
False

Choose one

1 point

On a pressure–volume diagram, what does the signed area enclosed by a complete cycle represent?

A
Net heat transfer over the cycle
B
Net boundary work over the cycle
C
The change in internal energy over the cycle
D
The working fluid's final pressure

Choose one

1 point

In a steady-flow power system, which description best matches the typical energy behavior of a turbine?

A
A turbine requires work to raise the fluid's pressure.
B
A turbine adds heat to the fluid at constant pressure.
C
A turbine typically produces work as the fluid's enthalpy decreases.
D
A turbine rejects heat to condense the fluid.

Written response

1 point

A power cycle receives $900\ \text{kJ}$ of heat and rejects $540\ \text{kJ}$ . What is its net work output? Give your answer in kJ and enter the number only.

Choose one

1 point

In a Rankine cycle, what does the pump do to the working fluid?

A
It rejects heat and returns the fluid to liquid.
B
It raises the pressure of the liquid.
C
It produces work as steam expands.
D
It adds heat to turn the pressurized liquid into steam.

Choose one

1 point

A refrigeration cycle absorbs $250\ \text{kJ}$ from a cold space and uses $80\ \text{kJ}$ of work. How much heat does it deliver to the warm surroundings?

A
$170\ \text{kJ}$
B
$250\ \text{kJ}$
C
$330\ \text{kJ}$
D
$400\ \text{kJ}$