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Units:

# Horsepower hour

This article has been reviewed by the following Topic Editor: Peter Saundry

#### Definition

Horsepower-hour is a unit of energy or work equal to the work done by one horsepower in one hour. Horsepower is the unit of power in the English system of measurement. The SI unit of energy is the joule.

One joule = 3.73·10-7horsepower-hour.

#### History

The term horsepower was coined by James Watt (1736-1819), the Scottish inventor and mechanical engineer renowned for his improvements of the steam engine. A horse, harnessed to an appropriate machine, can lift 550 pounds at the rate of 1 foot per second.

#### Conversions

1 horsepower-hour = 1.97·106 foot-pound
1 horsepower-hour = 6.42·102 kilocalorie (thermal)
1 horsepower-hour = 2.55·10s Btu (thermal)
1 horsepower-hour = 2.68·106 joules
1 horsepower-hour = 0.746 kilowatt-hours
1 horsepower-hour = 2.6813 ergs
1 horsepower-hour = 1.67·1025 electron-volts
1 horsepower-hour = 2.68·1013 dyne-centimeters

## Citation

Cutler J. Cleveland (Lead Author);Peter Saundry (Topic Editor) "Horsepower hour". In: Encyclopedia of Earth. Eds. Cutler J. Cleveland (Washington, D.C.: Environmental Information Coalition, National Council for Science and the Environment). [First published in the Encyclopedia of Earth December 22, 2006; Last revised Date December 22, 2006; Retrieved June 19, 2013 <http://www.eoearth.org/article/Horsepower_hour?topic=49549>

## The Author

Cutler J. Cleveland  is Professor of Earth and Environment at Boston University, where he also is on the faculty of the Center for Energy and Environmental Studies. Professor Cleveland is Editor-in-Chief of the Encyclopedia of Energy (Elsevier, 2004), winner of an American Library Association award, the Dictionary of Energy (Elsevier, 2005), Handbook of Energy (Elsevier, forthcoming), and is the Founding Editor-in-Chief of the Encyclopedia of Earth.  He is the recipient of the Adelma ... (Full Bio)