Physics

Temperature

Temperature

Measure of the average kinetic energy (KE) of molecules of an object, indicating how "hot" the object is.

Heat

Total kinetic energy (KE) and potential energy (PE) of the molecules in an object, transferred from one body to another due to a difference in temperature.

Internal Energy (U)

Total amount of KE and PE of all the particles in the system.

Heat Capacity

Amount of heat needed to change the temperature of an object by a degree, measured in joules per degree Celsius (J/Kg.C).

Heat Capacity formula

C = mc, where C is the heat capacity, m is the mass, and c is the specific heat in J/Kg.C.

Specific Heat

The amount of heat needed to change the temperature of a unit mass of a substance by 1 degree.

Specific Latent Heat of Fusion

The amount of thermal energy required to change the state of 1 kg of a substance from solid to liquid or vice versa.

Specific Latent Heat of Vaporization

The amount of thermal energy required to change the state of 1 kg of a substance from liquid to gas or vice versa.

Conduction

The transfer of heat through a diffusive process wherein molecules transmit their kinetic energy to other molecules by colliding with them.

Convection

The transfer of heat associated with the motion of the medium, such as when a hot material flows into a cold material.

Radiation

The transfer of heat via electromagnetic radiation, such as the radiation from the Sun.

1st Law of Thermodynamics

The law stating that the internal energy of a system is affected by the heat it absorbs (or releases) and the work done by the system or work done on the system.

Work

The transfer of energy resulting in a change in the state of a system.

Heat Engine

Device converting heat energy into continuous mechanical work.

1st Law of Thermodynamics

Total thermal energy change equals work done and heat added.

Specific Heat Equation

Q = mcΔT, calculating heat added or removed.

Mechanical Equivalent of Heat

J = 4.186 J/cal, relating mechanical energy to heat.

Adiabatic Process

Gas compression/expansion without heat exchange.

Thermal Efficiency

Measure of how well an engine converts heat to work.

Ideal Efficiency of a Carnot Engine

Eff = (QH - QC) / QH x 100%, for Carnot engines.

Second Law of Thermodynamics

Total entropy of a closed system increases over time.

Heat Pump

Device transferring heat from a colder to a warmer space.