• In physics, power (symbol: P) is the rate at which work is performed or energy is transmitted, or the amount of energy required or expended for a given unit of time. As a rate of change of work done or the energy of a subsystem, power is:


  • where P is power, W is work and t is time.

Units of power

  • Generally, it refers to the units of energy divided by time. The SI unit of power is the watt (W), which is equal to one joule per second. Non-SI units of power include ergs per second (erg/s) or horsepower (hp).
  • One unit of horsepower is equivalent to 33,000 foot-pounds per minute, or the power required to lift 550 pounds one foot in one second, and is equivalent to about 746 watts. (one pound = 0.453 kg)
Last modified: Wednesday, 3 August 2011, 8:35 AM