Power (physics) - Average Power

Average Power

As a simple example, burning a kilogram of coal releases much more energy than does detonating a kilogram of TNT, but because the TNT reaction releases energy much more quickly, it delivers far more power than the coal. If ΔW is the amount of work performed during a period of time of duration Δt, the average power Pavg over that period is given by the formula

P_\mathrm{avg} = \frac{\Delta W}{\Delta t}\,.

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 instantaneous power is then the limiting value of the average power as the time interval Δt approaches zero.

P = \lim _{\Delta t\rightarrow 0} P_\mathrm{avg} = \lim _{\Delta t\rightarrow 0} \frac{\Delta W}{\Delta t} = \frac{dW}{dt}\,.

In the case of constant power P, the amount of work performed during a period of duration T is given by:

W = PT\,.

In the context of energy conversion it is more customary to use the symbol E rather than W.

Read more about this topic:  Power (physics)

Famous quotes containing the words average and/or power:

    “Here is a golden Rule.... Write legibly. The average temper of the human race would be perceptibly sweetened, if everybody obeyed this Rule!”
    —Lewis Carroll [Charles Lutwidge Dodgson] (1832–1898)

    “... whilst you are proclaiming peace and good will to men, Emancipating all Nations, you insist upon retaining absolute power over wives. But you must remember that Arbitrary power is like most other things which are very hard, very liable to be broken—and notwithstanding all your wise Laws and Maxims we have it in our power not only to free ourselves but to subdue our Masters, and without violence throw both your natural and legal authority at our feet ...”
    —Abigail Adams (1744–1818)