Horsepower

Pronunciation

• enPR: hô(r)s'pou"É™r, IPA: /ˈhɔː(r)spaÊŠÉ™(r)/

Origin

• From horse and power, the unit originally defined as the amount of power that a horse could provide.

Noun

1. A non-metric unit of power (symbol hp) with various definitions, for different applications. The most common of them is probably the mechanical horsepower, approximately equal to 745.7 watts.
• 2012 March 22nd, David Blockley, Engineering: Very Short Introductions (309), Oxford University Press, ISBN 9780199578696, chapter 2: “The age of gravity – time for work”, page 20:In the past, before the widespread adoption of SI units, the work that engines were capable of doing was compared with the work that horses could do – hence the term ‘horsepower’. Various people came up with various equivalencies, but the modern agreed definition is that 1 horsepower is 746 joules per second or 746 watts.
2. A metric horsepower (symbol often PS from the German abbreviation), approximately equal to 735.5 watts.
3. Strengthpolitical horsepower

Derived terms

• horsepower-hour
• hydraulic horsepower
• mechanical horsepower
• thermal horsepower