1. Work
Work is said to be done when a force acts on an object and the object is displaced. Work
(W) = Force (F) × Displacement (s). SI unit: Joule (J).
- Positive Work: Force and displacement are in the same direction.
- Negative Work: Force and displacement are in opposite directions (e.g.,
friction).
- Zero Work: Force and displacement are perpendicular (e.g., carrying a load
horizontally).
2. Energy
The capacity of doing work is called energy. Types include:
- Kinetic Energy (Eₖ): Energy of an object due to its motion. Eₖ =
½mv².
- Potential Energy (Eₚ): Energy of an object due to its position or
configuration. Gravitational potential energy Eₚ = mgh.
3. Law of Conservation of Energy
Energy can only be transformed from one form to another; it can neither be created nor
destroyed. The total energy before and after transformation remains constant.
4. Power
The rate of doing work or the rate of transfer of energy. Power (P) = Work / Time. SI
unit: Watt (W). Commercial unit: kWh.