FORMS OF ENERGY
Energy can exist in numerous forms such as thermal, mechanical, kinetic, potential, electric, magnetic, chemical, and nuclear, and their sum constitutes the total energy, E of a system.
•Thermodynamics deals only with the change of the total energy.
•Macroscopic forms of energy: Those a system possesses as a whole with respect to some outside reference frame, such as kinetic and potential energies.
•Microscopic forms of energy: Those related to the molecular structure of a system and the degree of the molecular activity.
•Internal energy, U: The sum of all the microscopic forms of energy.
The macroscopic energy of an object changes with velocity and elevation.
•Kinetic energy, KE: The energy that a system possesses as a result of its motion relative to some reference frame.
•Potential energy, PE: The energy that a system possesses as a result of its elevation in a gravitational field.