Open Systems and Work: Understanding Work Interactions in Thermodynamics

Question 1

Boundary work done on an open system depends on all of the following factors EXCEPT:

Accepted Answer

Heat transfer across the boundary

Answer

Pressure difference across the boundary

Answer

Volume change of the system

Answer

Displacement of the boundary

Question 2

In an open system, the work done by the system is:

Accepted Answer

Positive if the system expands against an external force

Answer

Negative if the system contracts against an external force

Answer

Zero if there is no volume change

Answer

Always positive

Question 3

The work done by a pump is:

Accepted Answer

Positive if it adds energy to the fluid

Answer

Negative if it removes energy from the fluid

Answer

Always positive

Answer

Always negative

Question 4

A piston-cylinder arrangement contains a gas. The piston is moved outward, causing the gas to expand. In such a scenario, which of the following is true regarding the work done by the gas?

Accepted Answer

The gas does positive work

Answer

The gas does negative work

Answer

The work done is zero

Answer

The sign of the work depends on the direction of piston movement

Question 5

Which of the following is NOT an example of an open system?

Accepted Answer

A closed container of gas

Answer

A steam engine

Answer

A turbine

Answer

A refrigerator

Question 6

A gas is flowing through a pipe. The pressure at the inlet is higher than the pressure at the outlet. Considering this flow, which of the following is true regarding the work done by the gas?

Accepted Answer

The gas does positive work

Answer

The gas does negative work

Answer

The work done is zero

Answer

The sign of the work depends on the mass flow rate of the gas

Question 7

Which of the following devices converts thermal energy into mechanical work?

Accepted Answer

Steam turbine

Answer

Heat exchanger

Answer

Condenser

Answer

Evaporator

Question 8

Identify an example of an open system in engineering applications.

Accepted Answer

A jet engine

Answer

A closed-loop steam power plant

Answer

A refrigerator

Answer

A solar panel

Question 9

Define an open system in thermodynamics.

Accepted Answer

A system with a boundary that allows both mass and energy transfer

Answer

A system with a fixed boundary that allows no mass or energy transfer

Answer

A system with a boundary that allows mass but not energy transfer

Answer

A system with a boundary that allows energy but not mass transfer

Question 10

In an open system, the change in internal energy is:

Accepted Answer

Equal to the net heat transfer minus the net work done

Answer

Equal to the net heat transfer plus the net work done

Answer

Equal to the net work done minus the net heat transfer

Answer

Independent of heat transfer and work done

Question 11

Which of the following is an example of an open system?

Accepted Answer

Mixing of two fluids in a common container

Answer

Adiabatic expansion of an ideal gas

Answer

Isothermal compression of a closed system

Answer

Heat transfer through a solid wall

Question 12

The work done by an engine during the expansion stroke is:

Accepted Answer

Positive

Answer

Negative

Answer

Zero

Answer

Dependent on the engine type

Question 13

In thermodynamics, an open system is characterized by:

Accepted Answer

Allowing the exchange of both mass and energy with the surroundings

Answer

Allowing the exchange of energy but not mass with the surroundings

Answer

Allowing the exchange of mass but not energy with the surroundings

Answer

Exchanging neither mass nor energy with the surroundings

Question 14

In an open system where a fluid is compressed by a piston, the work interactions include:

Accepted Answer

Both work done by the fluid on the surroundings and work done on the fluid by the surroundings

Answer

Work done by the fluid on the surroundings

Answer

Work done on the fluid by the surroundings

Answer

Neither work done by the fluid on the surroundings nor work done on the fluid by the surroundings

Question 15

In an open system, if heat is transferred into the system at a rate of 100 W and work is done on the system at a rate of 50 W, the rate of change in internal energy is:

Accepted Answer

150 W

Answer

50 W

Answer

100 W

Answer

0 W

Question 16

Which of the following is NOT a form of work interaction in an open system?

Accepted Answer

Heat transfer

Answer

Boundary work

Answer

Shaft work

Answer

Electrical work

Question 17

According to the first law of thermodynamics, the change in internal energy of an open system is equal to:

Accepted Answer

Heat added to the system minus work done by the system

Answer

Heat added to the system plus work done by the system

Answer

Work done on the system minus heat added to the system

Answer

Work done on the system plus heat added to the system

Question 18

Which of the following assumptions is valid for applying the first law to open systems?

Accepted Answer

Mass can enter or leave the system

Answer

The system is in equilibrium

Answer

The process is isothermal

Answer

Heat transfer is negligible

Question 19

In an isobaric process, the pressure of the system remains constant. What is the work done by the system?

Accepted Answer

W = P(V2 - V1)

Answer

W = -P(V2 - V1)

Answer

W = ΔU

Answer

W = 0

Question 20

Which of the following devices is an example of an open system in thermodynamics?

Accepted Answer

Car engine

Answer

Refrigerator

Answer

Thermos

Answer

Battery

Question 21

The power developed by an open system is given by:

Accepted Answer

W / Δt

Answer

-W / Δt

Answer

ΔU / Δt

Answer

Q / Δt

Question 22

In thermodynamics, an open system is characterized by the ability for:

Accepted Answer

Both matter and energy to enter or leave the system

Answer

Matter to enter or leave the system

Answer

Energy to enter or leave the system

Answer

Neither matter nor energy to enter or leave the system

Question 23

A steam turbine is an example of which type of open system?

Accepted Answer

Steady-flow

Answer

Unsteady-flow

Answer

Transient

Answer

Cyclic

Question 24

In a steady-flow open system, the rate of mass entering the system is:

Accepted Answer

Equal to the rate of mass leaving the system

Answer

Greater than the rate of mass leaving the system

Answer

Less than the rate of mass leaving the system

Answer

Varies over time

Question 25

Which property of an open system measures its work potential?

Accepted Answer

ExERGY

Answer

Enthalpy

Answer

Entropy

Answer

Gibbs free energy

Question 26

Which of the following processes is an example of a work-producing process in thermodynamics?

Accepted Answer

Adiabatic compression

Answer

Isothermal expansion

Answer

Adiabatic expansion

Answer

Isobaric compression

Question 27

Which process is considered reversible?

Accepted Answer

Isothermal expansion

Answer

Adiabatic compression

Answer

Heat transfer through a temperature gradient

Answer

Friction

Question 28

In a piston-cylinder arrangement, an outward movement of the piston against constant external pressure leads to an increase in system volume. Which statement is true?

Accepted Answer

Work is done by the system

Answer

Work is done on the system

Answer

No work is done

Answer

The sign of work depends on piston movement direction

Question 29

For a steady-flow nozzle, which expression represents the work done by the nozzle per unit mass of fluid?

Accepted Answer

Change in kinetic energy

Answer

Pressure drop across the nozzle

Answer

Change in potential energy

Answer

Internal energy change

Question 30

The thermal efficiency of an engine is defined as the ratio of:

Accepted Answer

Work output to heat input

Answer

Heat input to work output

Answer

Internal energy change to heat input

Answer

Heat output to work input