1st Law
Energy conservation during transformation Quantity
Energy, Heat and the First Law
Conservation of Energy Principle (1st Law)
Energy can be neither created or destroyed during a process, it can only change forms
Although energy is conserved, the fraction of ‘useful’ energy reduces due to the 2nd law.
Energy Balance
Heat, work and mass cross the boundary from the system to its surroundings.
L.S is change of internal energy, R.S is the energy transfer form heat, mass, energy etc.
Internal Energy
All matter has internal energy which is energy associated with molecular structure and activity
Thermal Energy
See Thermal Energy
1st Law of Thermo in a Closed System
Now for a system which is:
- Closed (No mass transfer)
- ‘Stationary’ ()
For the internal energy of a system:
On the right hand side, we are concerned with “processes”
Energy, Heat and the First Law
Conservation of Energy Principle (1st Law)
Energy can be neither created or destroyed during a process, it can only change forms
Although energy is conserved, the fraction of ‘useful’ energy reduces due to the 2nd law.
Energy Balance
Heat, work and mass cross the boundary from the system to its surroundings.
L.S is change of internal energy, R.S is the energy transfer form heat, mass, energy etc.
Internal Energy
All matter has internal energy which is energy associated with molecular structure and activity
For the internal energy of a system:
On the right hand side, we are concerned with “processes”
More generally:
and
where these are all time derivatives.