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:

    “That’s one thing I like about Hollywood. The writer is there revealed in his ultimate corruption. He asks no praise, because his praise comes to him in the form of a salary check. In Hollywood the average writer is not young, not honest, not brave, and a bit overdressed. But he is darn good company, which book writers as a rule are not. He is better than what he writes. Most book writers are not as good.”
    —Raymond Chandler (1888–1959)

    “The only wealth in this world is children, more than all the money, power on earth.”
    —Mario Puzo, U.S. author, screenwriter, and Francis Ford Coppola, U.S. director, screenwriter. Michael Corleone (Al Pacino)