Power | |
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Common symbols | P |

SI unit | watt (W) |

In SI base units | kg⋅m^{2}⋅s^{−3} |

Derivations from other quantities | |

Dimension |

Part of a series on |

Classical mechanics |
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energy transferred or converted per unit time. In the International System of Units, the unit of power is the watt, equal to one joule per second. In older works, power is sometimes called activity.^{[1]}^{[2]}^{[3]} Power is a scalar quantity.
The output power of a motor is the product of the torque that the motor generates and the angular velocity of its output shaft. The power involved in moving a ground vehicle is the product of the traction force on the wheels and the velocity of the vehicle. The power of a jet-propelled vehicle is the product of the engine thrust and the velocity of the vehicle. The rate at which a light bulb converts electrical energy into light and heat is measured in watts – the electrical energy used per unit of time. ## DefinitionPower is the rate with respect to time at which work is done; it is the time derivative of work: where If a
If instead the force is variable over a three-dimensional curve C, then the work is expressed in terms of the line integral:
From the fundamental theorem of calculus, we know that . Hence the formula is valid for any general situation. ## UnitsThe dimension of power is energy divided by time. In the International System of Units (SI), the unit of power is the watt (W), which is equal to one joule per second. Other common and traditional measures are horsepower (hp), comparing to the power of a horse; one ## Average powerAs a simple example, burning one kilogram of coal releases much more energy than does detonating a kilogram of TNT, It is the average amount of work done or energy converted per unit of time. The average power is often simply called "power" when the context makes it clear. The |