Power of a body is defined as the rate at which the body can do the work.

(1) **Dimension :** [P] = [ML^{2}T^{–3}]

(2) **Units :** Watt or Joule/sec [S.I.]

**Practical Units :** Kilowatt (kW), Mega watt (MW) and Horse power (hp)

Relations between different units : 1 watt = 1 Joule/sec = 10^{7} erg/sec

1hp = 746 Watt

(3) The slope of work time curve gives the instantaneous power. As P = dW/dt = tan θ