AP Physics: Thermodynamics flashcards

Question 1

What is a process called in which no heat is exchanged?

Accepted Answer

An adiabatic process

Question 2

What is a process called in which the volume stays constant?

Accepted Answer

An isochoric process

Question 3

What is a process called in which the temperature stays constant?

Accepted Answer

An isothermal process

Question 4

What do you call a constant-pressure process during which the gas does work?

Accepted Answer

An isobaric process

Question 5

Which cycle uses only reversible processes, namely adiabatic and isothermal ones?

Accepted Answer

The Carnot cycle

Question 6

What is a heat engine that runs on a Carnot cycle called?

Accepted Answer

A Carnot engine

Question 7

What is the highest theoretically possible efficiency of a heat engine called?

Accepted Answer

The Carnot efficiency

Question 8

What is a process called whose path ends back at the starting state after each cycle?

Accepted Answer

A cyclical process

Question 9

What do you call a device that turns heat flow into mechanical work?

Accepted Answer

A heat engine

Question 10

What do you call a machine that moves heat from a colder place to a hotter one?

Accepted Answer

A heat pump

Question 11

Which law says the internal energy of a system changes by the net heat added minus the net work the system does?

Accepted Answer

The first law of thermodynamics

Question 12

What is the total of the kinetic and potential energies of the particles making up a system called?

Accepted Answer

Its internal energy

Question 13

Of heat transfer, work and the change in internal energy, which one does not depend on the path between two states?

Accepted Answer

The change in internal energy

Question 14

Which law says heat flows spontaneously from hotter to colder bodies, never spontaneously the other way?

Accepted Answer

The second law of thermodynamics

Question 15

Which law rules out a heat engine turning all of its heat input into work in a cyclical process?

Accepted Answer

The second law of thermodynamics

Question 16

Which law says total entropy either increases or stays constant and never decreases?

Accepted Answer

The second law of thermodynamics

Question 17

On a pressure-volume diagram, what represents the work done by a gas in going from one state to another?

Accepted Answer

The area under the curve

Question 18

On a pressure-volume diagram, what represents the net work of a cyclical process?

Accepted Answer

The area enclosed by the loop

Question 19

In which direction must a cycle be traced on a pressure-volume diagram for the net work to be positive (work output)?

Accepted Answer

Clockwise

Question 20

How much work does a gas do in an isochoric process, and why?

Accepted Answer

None, because the volume does not change

Question 21

The efficiency of a heat engine is its net work output divided by what?

Accepted Answer

The heat transfer into the engine from the hot reservoir

Question 22

Which cycle, made of two adiabatic and two isochoric processes, models the four-stroke gasoline engine?

Accepted Answer

The Otto cycle

Question 23

Which kind of engine has the greatest possible efficiency among all heat engines working between the same two temperatures?

Accepted Answer

A Carnot engine (any engine using only reversible processes)

Question 24

What ratio of temperatures sets a Carnot engine's efficiency, and what is the formula?

Accepted Answer

Cold to hot reservoir temperature, in kelvins; efficiency = 1 - Tc/Th

Question 25

Heat pumps, air conditioners and refrigerators are essentially what kind of device run backward?

Accepted Answer

Heat engines

Question 26

For a heat pump, the coefficient of performance is the heat delivered to the hot side divided by what?

Accepted Answer

The work input

Question 27

For a refrigerator or air conditioner, the coefficient of performance is the heat removed from the cold side divided by what?

Accepted Answer

The work input

Question 28

What quantity measures a system's disorder and the unavailability of its energy to do work?

Accepted Answer

Entropy

Question 29

What is the SI unit of entropy?

Accepted Answer

Joules per kelvin (J/K)

Question 30

For a reversible process, the change in entropy equals the heat transfer divided by what?

Accepted Answer

The absolute temperature at which it occurs

Question 31

Does entropy depend on how a system reached its state?

Accepted Answer

No, it is a property of state, like internal energy

Question 32

Can entropy fall in one region of the universe without breaking the second law?

Accepted Answer

Yes, provided the total entropy of the universe increases

Question 33

What is the final state of maximum entropy, where no work is possible, called?

Accepted Answer

The heat death of the universe

AP Physics: Thermodynamics flashcards

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