This site is devoted to explaining how physics can be applied to horses and equestrian jumping.  However, if you’re hoping to find something that applies more to everyday life, this is it.  The “horsepower” is exactly what it sounds like…it is a unit that describes the amount of power something exerts, based on the power of horses.

    The term horsepower was coined by James Watt, the inventor of the steam engine, when he needed a unit of power large enough to describe the output of his new invention.  He worked in a coal mine and observed the work of the ponies that were used in the mine to haul coal.  He saw that a mine pony could do about 22,000 foot-pounds of work in a minute.  He then increased that number by 50% to make the measurement of horsepower (not ponypower!) at 33,000 foot-pounds of work in one minute.  So, according to Watt, a horse can haul 330 pounds of coal 100 feet in one minute.  Thanks to Watt’s unit of measurement, horses can be applied to many things in every day life…cars, lawnmowers, even vacuum cleaners!

There are several conversions between horsepower and more familiar units:

• One horsepower is equal to 746 watts (which is named for the same guy we’ve been talking about!).  So according to Watt, one horse working at 33,000 foot-pounds could exert enough power to run a generator producing a continuous 746 watts.
• One horsepower is equal to 2.545 British thermal units (BTU), and a BTU is the amount of energy   needed to raise the temperature of one pound of water one degree Fahrenheit.
•  One horsepower is equal to 641 dietary Calories, so the average horse burns 641 Calories per hour when it is doing 33,000 foot-pounds of work.