kilowatt-hour

(noun)

a unit of electrical energy equal to that done by one kilowatt acting for one hour; equal to 3.6 mega-joules. Symbol: kWh.

Examples of kilowatt-hour in the following topics:

  • Energy Usage

    • However, typically, residential energy bills state household energy consumption in kilowatt-hours (kWh).
    • We can parse out the conversion from kilowatt-hours to joules in this way: 1 W = 1 J/s and a kilowatt is 1000 W while one hour is 3,600 seconds, so 1 kWh is (1000 J/s)(3600 s)=3,600,000 joules.
    • This is the scale of American home energy usage, which is on the order of hundreds of kilowatt-hours per month.

  • Work Done by a Variable Force

    • Non-SI units of work include the erg, the foot-pound, the foot-pound, the kilowatt hour, the liter-atmosphere, and the horsepower-hour.

  • What is Power?

    • Sunlight reaching Earth's surface carries a maximum power of about 1.3 kilowatts per square meter (kW/m2).

  • Converting Units

    • For example, 10 miles per hour can be converted to meters per second by using a sequence of conversion factors.
    • So, when the units mile and hour are cancelled out and the arithmetic is done, 10 miles per hour converts to 4.47 meters per second.

  • Fluorescence and Phosphorescence

    • As these transitions occur very slowly in certain materials, absorbed radiation may be re-emitted at a lower intensity for up to several hours after the original excitation.
    • Typically the glowing then slowly fades out within minutes (or up to a few hours) in a dark room.

  • Convection

    • The air in a typical house is completely replaced in less than an hour.
    • Newly constructed homes are designed for a turnover time of 2 hours or more, rather than 30 minutes for the house of this example.
    • More extreme measures are sometimes taken in very cold (or hot) climates to achieve a tight standard of more than 6 hours for one air turnover.

  • Rotational Kinetic Energy: Work, Energy, and Power

    • As the Earth has a period of about 23.93 hours, it has an angular velocity of 7.29×10−5 rad/s.

  • B.14 Chapter 12

    • yielding accretion times of 2.8 hours and 24 years, respectively.
    • Type-I bursts typically recur on a timescale of hours at one-tenth of the Eddington accretion rate.

  • Prefixes and Other Systems of Units

    • These can include the minute, hour, and day used in temporal measurements, the liter for volumetric measurements, and the degree, minute, and second used to measure angles.

  • Particle-Wave Duality

    • The wavelength of the matter wave associated with a baseball, say moving at 95 miles per hour, is extremely small compared to the size of the ball so that wave-like behavior is never noticeable.