The capacity to do work or the ability to cause changes.
Total energy is denoted by .
Here:
- internal energy
- kinetic energy of the system
- the potential energy of the system
Microscopic Energy
The energy possessed by individual particles or molecules within a system. Associated with the motion and interactions of these particles at the atomic and molecular level. Denoted by .
Examples:
- Thermal energy from random molecular motion in steam
- Chemical energy stored in fuel molecules
Internal Energy
Sum of all microscopic energies of a system.
Macroscopic Energy
The energy associated with the bulk properties of a system. Such as its temperature, pressure, and volume. It is the energy that can be measured and observed at the macroscopic scale.
Examples:
- Kinetic energy of a moving car
- Potential energy of water behind a dam
Heat & Work
Has only meaning in transitions. Can be identified only when crossing the system boundary.
Called path functions as they depends on the path taken.
