Physics: An Introduction Chapter 18 -- Reference Tools & Resources

Chapter 18: The Laws of Thermodynamics
Reference Tools & Resources

Reference Tools & Resources

I. Key Terms and Phrases

state function: a quantity that only depends on the thermodynamic state of a system (determined by P, V, and T).

reversible process: a process that allows a system to return precisely to a previous state.

irreversible process: a process that is not reversible.

isothermal process: a process that takes place at constant temperature.

adiabatic process: a process during which no heat is transferred.

molar specific heat: the heat needed to change the temperature of one mole of a substance by one Celsius degree.

heat engine: a device that converts heat into work.

Carnot's theorem: the theorem that states the conditions that give the maximum efficiency of a heat engine.

refrigerator: a device that uses work to cause heat to flow from a cooler region to a warmer region.

entropy: the ratio of the heat that flows at a fixed temperature for a reversible process. It measures the amount of disorder in a system.

II. Important Equations

Name/Topic Equation Explanation
the first law of thermodynamics DU = Q - W The conservation of energy for systems with heat flow.

constant pressure processes W = P(DV) The work done by a gas expanding under constant pressure.

constant temperature processes The work done by a gas expanding under constant temperature.

specific heats The molar specific heat at constant volume and at constant pressure.

adiabatic processes The behavior of an ideal gas during an adiabatic process.

heat engines The efficiency of a heat engine.

entropy The change in entropy of a system, at fixed temperature, under a reversible process.

Name/Topic	Equation	Explanation
the first law of thermodynamics	DU = Q - W	The conservation of energy for systems with heat flow.
constant pressure processes	W = P(DV)	The work done by a gas expanding under constant pressure.
constant temperature processes		The work done by a gas expanding under constant temperature.
specific heats		The molar specific heat at constant volume and at constant pressure.
adiabatic processes		The behavior of an ideal gas during an adiabatic process.
heat engines		The efficiency of a heat engine.
entropy		The change in entropy of a system, at fixed temperature, under a reversible process.

III. Know Your Units

Quantity Dimension SI Unit
molar specific heat (C) [M][L²][T^-2][K^-1]

efficiency (e) dimensionless --

coefficient of performance (COP) dimensionless --

entropy (S) [M][L²][T^-2][K^-1] J/K

Quantity	Dimension	SI Unit
molar specific heat (C)	[M][L²][T^-2][K^-1]
efficiency (e)	dimensionless	--
coefficient of performance (COP)	dimensionless	--
entropy (S)	[M][L²][T^-2][K^-1]	J/K