horse power

[bob72]

What does horse power really mean

[Clanad]

The amount of work required to lift 33,000 pounds 1 foot in 1 minute...

[Quizmonster]

Horsepower is the power developed in the cylinder(s) of an engine. Some of this is absorbed by friction in various engine-parts. The power that remains - ie the power that can actually be used - is called 'brake horsepower'. It was so-called because the level of power was measured by means of applying a brake to stop the engine-shaft from turning. After Watt and his steam engine developments, 1 HP became a conventional mechanical unit described as "550 foot pounds per second"
To give you some idea of the "horse" significance, this is roughly about half as strong again as a real horse!

[Space]

It is a unit of power, not work.
Fortunately the metric system was also invented...
1 hp = 746 W

[Gef]

Actually, for metric conversions 1hp = 735.499 watts.

Have a look here for everything you (n)ever wanted to know about units.

http://www.ex.ac.uk/cimt/dictunit/dictunit.htm#power