Physics: An Introduction Chapter 16 -- Reference Tools & Resources

Chapter 16: Temperature and Heat
Reference Tools & Resources

Reference Tools & Resources

I. Key Terms and Phrases

temperature: the property of systems that determines the existence and direction of the heat flow between them when they are in thermal contact.

heat: the energy that is transferred between systems when it is possible for heat to flow beween them.

thermal contact: exists between systems when it is possible for heat to flow between them.

thermal equilibrium: exists when systems are brought into thermal contact, no heat transfer occurs.

zeroth law of thermodynamics: the fundamental law that allows a working definition of temperature.

absolute zero: the lower limit on physically attainable temperatures (the zero temperature on the Kelvin scale).

coefficient of expansion: the substance dependent proportionality factor that determines how much an object will expand as the result of a temperature change.

calorie: a unit of energy equal to the heat needed to raise the temperature of 1 gram of water by 1 Celsius degree.

British Thermal Unit: a unit of energy equal to the heat needed to raise the temperature of 1 pound of water by 1 Fahrenheit degree.

heat capacity: a quantity that determines how much heat is needed to change the temperature of an object by a certain amount.

specific heat: a quantity that determines how much heat is needed to change the temperature of a unit mass of an object by a certain amount.

conduction: heat transfer by direct flow through an object due to a temperature difference across it.

thermal conductivity: a quantity that determines the rate at which heat conducts through a given object.

convection: heat transfer by direct movement of matter from one place to another.

radiation: heat transfer by emitting or absorbing electromagnetic waves.

Stefan-Boltzmann constant: a fundamental constant that determines the rate at which an object emits or absorbs radiation.

emissivity: a dimensionless quantity between 0 and 1 that measures how effectively an object radiates heat.

II. Important Equations

Name/Topic Equation Explanation
temperature scales
T = T_C + 273.15 The conversions between Celsius and Fahrenheit and between Kelvin and Celsius.

thermal expansion
The change in size of an object or substance due to a temperature change.

specific heat Q = mcDT The heat needed to change the temperature of an amount of mass, m, of a substance by DT.

conduction The heat that conducts through an object of length L and cross-sectional area A in time t.

radiation The rate of heat transfer by electromagnetic radiation.

Name/Topic	Equation	Explanation
temperature scales	T = T_C + 273.15	The conversions between Celsius and Fahrenheit and between Kelvin and Celsius.
thermal expansion		The change in size of an object or substance due to a temperature change.
specific heat	Q = mcDT	The heat needed to change the temperature of an amount of mass, m, of a substance by DT.
conduction		The heat that conducts through an object of length L and cross-sectional area A in time t.
radiation		The rate of heat transfer by electromagnetic radiation.

III. Know Your Units

Quantity Dimension SI Unit
temperature(T) [K] K

heat (Q) [M][L²][T^-2] J

coefficient of expansion (a), (b) [K^-1] K^-1

heat capacity [M][L²][T^-2][K^-1] J/K

specific heat (c) [L²][T^-2][K^-1]

thermal conductivity (k) [M][L][T^-3][K^-1]

Stefan-Boltzmann constant () [M][T^-3][K^-4]

emissivity (e) dimensionless --

Quantity	Dimension	SI Unit
temperature(T)	[K]	K
heat (Q)	[M][L²][T^-2]	J
coefficient of expansion (a), (b)	[K^-1]	K^-1
heat capacity	[M][L²][T^-2][K^-1]	J/K
specific heat (c)	[L²][T^-2][K^-1]
thermal conductivity (k)	[M][L][T^-3][K^-1]
Stefan-Boltzmann constant ()	[M][T^-3][K^-4]
emissivity (e)	dimensionless	--