Thermal Energy Transfer
Internal Energy
Internal Energy (U) = The sum of the randomly distributed
kinetic energies and potential energies of all of the particles
in a body.
Kinetic Energy comes from the speed of the molecules (1/2 x
mv^2).
Potential energy comes from the separation of the molecules.
Gasses have the highest internal energy compared to solids which
have the lowest.
Thermal Energy Transfer 1
, Changing internal energy
Increase Decrease
Doing work on it Changing state (melting or
evaporating)
Heating it up (increasing
the kinetic energy of the Cooling down
molecules)
First Law of Thermodynamics:
The internal energy of a system is increased when
energy is transferred to it by heating or when
work is done on it.
- This law is applicable in all situations, not just gasses.
Examples
When a gas expands its internal energy decreases because
the gas has had to do work on the surroundings.
When a gas is compressed its internal energy increases
because the work has been done on the gas by the
surroundings
Thermal Energy Transfer 2
Internal Energy
Internal Energy (U) = The sum of the randomly distributed
kinetic energies and potential energies of all of the particles
in a body.
Kinetic Energy comes from the speed of the molecules (1/2 x
mv^2).
Potential energy comes from the separation of the molecules.
Gasses have the highest internal energy compared to solids which
have the lowest.
Thermal Energy Transfer 1
, Changing internal energy
Increase Decrease
Doing work on it Changing state (melting or
evaporating)
Heating it up (increasing
the kinetic energy of the Cooling down
molecules)
First Law of Thermodynamics:
The internal energy of a system is increased when
energy is transferred to it by heating or when
work is done on it.
- This law is applicable in all situations, not just gasses.
Examples
When a gas expands its internal energy decreases because
the gas has had to do work on the surroundings.
When a gas is compressed its internal energy increases
because the work has been done on the gas by the
surroundings
Thermal Energy Transfer 2
