Define Work, Power and Energy and State Their SI units


Work is said to be done when an object is displaced from its initial position under the action of a force. Work is measured as the scalar product of the applied force and the displacement of the object.

Work done (W) is conventionally defined as W = Fscosθ


Work done in unit time is called power.
Hence, power (P) = work (W) / time (t)
or, P = W/t


A body can do work by the transfer of some amount of energy. Energy is the capacity of doing work.

The total amount of work that a body can do is the same as its total amount of energy. Hence, energy and work are equivalent physical quantities, having the same units and dimensions. Both are scaler quantities.

Energy is manifested in nature in different forms:

  • Mechanical Energy
  • Heat Energy
  • Light Energy
  • Sound Energy
  • Magnetic Energy
  • Electrical Energy
  • Chemical Energy
  • Atomic Energy