Power of a person or machine is defined as the time rate at which work is done or energy is transferred by it.

If a person does work W in time t, then its average power is

## Instantaneous Power

The instantaneous power of an agent is defined as the limiting value of the average power of an agent in a small time interval, when the time interval approaches to zero.

If ∆W work is done in the small time interval ∆t, then the instantaneous power is given by

Thus, the power of an agent at any instant is equal to the dot product of its force and velocity vectors at that instant.

##### Dimensional Formula

The Dimentional formula of Power is [ML²T⁻³].

##### Units Of Power

The SI unit of Power is Watt(W).

Another popular units of Power are Kilowatt and Horsepower.

1 Kilowatt = 1000 Watt

1 Horsepower = 746 Watt

**NCERT Class 11 Physics Book PDF Free Download**

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##### NCERT Class 11 Physics Hand Written Notes Chapter-Wise

**Chapter-1 (Physical World) PDF Free Download**

**Chapter-2 (Units and Measurement) PDF Free Download**

**Chapter-3 (Motion In A Straight Line) PDF Free Download**

**Chapter-4 (Motion In A Plane) PDF Free Download**

**Chapter-5 (Laws Of Motion) PDF Free Download**

**Chapter-6 (Work, Energy and Power) PDF Free Download**