Important Equations

Q = m L

l = length 

lo = length 

a = coefficient of linear expansion

Q = Thermal Energy (Heat)

c = Specific heat

L = Latent heat 


    Heat is a measure of how much thermal energy is transmitted from one body to another. We cannot say a body “has” a certain amount of heat any more than we can say a body “has” a certain amount of work. While both work and heat can be measured in terms of joules, they are not measures of energy but rather of energy transfer. A hot water bottle has a certain amount of thermal energy; when you cuddle up with a hot water bottle, it transmits a certain amount of heat to your body.

Definition provided by sparknote

Latent Heat

Latent heat is the name given to energy which is either lost or gained by a substance when it changes state, for example from gas to liquid. It is measured as an amount of energy, joules, rather than as a temperature.

Most substances can exist in three states: gas, liquid and solid, though there is an additional state named plasma. The main difference between a substance in each state is how quickly its molecules are moving. As a liquid, the molecules move at a speed where they can repeatedly join together, break apart, then join together again. When they move slowly, they stay joined together, forming a solid. When they move quickly, they stay broken apart, forming a gas.

Definition provided by Wisegeek


While temperature is related to thermal energy, there is no absolute correlation between the amount of thermal energy (heat) of an object and its temperature. Temperature measures the concentration of thermal energy in an object in much the same way that density measures the concentration of matter in an object. As a result, a large object will have a much lower temperature than a small object with the same amount of thermal energy.

Definition provided by sparknote

Specific heat

Specific heat is a measurement used in thermodynamics and calorimetry that states the amount of heat energy necessary to increase the temperature of an object by some unit of temperature. Specific heat specifically refers to the amount of heat energy required to raise a single kilogram of some substance by one Kelvin. It follows that if twice as much heat is added to a substance, its temperature should increase by twice as much. Specific heat is usually expressed in joules, the unit used in physics to describe energy.

 Definition provided by Wisegeek