Proof of 1 hp equal to 746 watts

They are both measurements of power, the rate at which work is done,

 i.e. work/time = force x distance/time

James Watt calculated the work output of a draught horse to be about 33,000 ft.lbf/min and called it one horsepower. However, one horsepower can mean different amounts of power depending on the applications used. Aaargh!

Hence we now use the metric system which is interchangeable between all the forms of power: mechanical, electrical, chemical etc., and the arithmetic is a lot easier too.

1 Watt = 1 Joule/second = 1 Newton.metre/second = 1 kg.m^2/s^3 = 1 volt.amp, etc.

There are two definitions for the horsepower.

According to the classical definition it is equal to 550 foot pounds per second.This works out to be 746 watts.

The metric horsepower is defined as 75 metre kilograms per second. This works out to be about 735 watts.

Proof of 1 hp equal to 746 watts

HP = Horsepower

HP and Watts are both units of power. Power can be electric or mechanical, and can be converted between the two. Any conversion will be less than 100 % efficient.

It is only for historic reasons that electrical power is measured in Watts not hp, like the way that tyre widths are in mm but rim diameter are in inches.

One pound is 4.44822 Newtons

so 550 foot pounds per seconds, converted to metric, is 550 x 0.3048 x 4.44822 Newton meters per second, which is 745.7 Newton meters per second, better known as Watts.

One foot is 0.3048 metres

1HP = 550 Foot Pound per second

1 Pound = 4.44822 Newtons

1 Foot is 0.3048 Meters.

1 HP = 550 * 4.44822 * 0.3048 meters

1Hp = 745.69 Newton meter per second.

Say 746 watts.

 James Watt invented a condensing steam engine which was very much more economical than the few Newcomen steam engines then in use for pumping water out of mines. He knew that mine-owners could easily compare pumping engines with the horse tread-mills then in use for pumping mines. He decided on a value of 550 ft.lb per minute for his horse-power which is a handy amount more than a horse can lift, day after day. (It has been tried, and the horse died after a 10 hour shift!) This meant that mine-owners could not argue the merits of his new device. 550 ft.lb/min is now given as 746 watts per HP using the power unit named for him. His steam engine was an unqualified success, with several hundred exported world-wide. Puimping engines put out 10 to 15 hp on average! This was the beginning of the First Industrial Revolution in 1770 in England.

The electrical energy consumption daily id measured in units. Hence, when we are talking of units, we are talking of energy. However, watt is a measure of power. Also, we know from the elementary formula,

Power=energy/ time

Hence, this gives us “watt-hour” as a measure of energy. Now we can effectively devise a relationship between watthour and unit.

1 unit= 1 KWh or 1000 Wh.

The following definitions have been or are widely used:^{[citation needed]}

Mechanical horsepower hp(I)	≡ 33,000 ft·lbf/min = 550 ft⋅lbf/s = 550 × 0.3048 × 9.80665 × 0.45359237 kg⋅m2/s3 ≈ 17,696 lbm⋅ft2/s3 ≈ 745.69987 W ≈ 76.04 kgf⋅m/s ≈ 76.04 kg × 9.80665 m/s2 × 1 m/s
Metric horsepower hp(M) – also PS, KM, cv, hk, pk, ks or ch	≡ 75 kgf⋅m/s ≡ 75 kg × 9.80665 m/s2 × 1 m/s ≡ 735.49875 W ≈ 542.476038840742 ft⋅lbf/s
Electrical horsepower hp(E)	≡ 746 W
Boiler horsepower hp(S)	≡ 33,475 BTU/h = 9,812.5 W
Hydraulic horsepower	= flow rate (US gal/min) × pressure (lbf/in2) × 7/12,000 or = flow rate (US gal/min) × pressure (lbf/in2) / 1714 = 550 ft⋅lbf/s = 745.69987 W
Air horsepower	=flow rate (cubic feet / minute) × pressure (inches water column) / 6,356 or = 550 ft⋅lbf/s = 745.69987 W

In certain situations it is necessary to distinguish between the various definitions of horsepower and thus a suffix is added: hp(I) for mechanical (or imperial) horsepower, hp(M) for metric horsepower, hp(S) for boiler (or steam) horsepower and hp(E) for electrical horsepower.

1 mechanical horsepower is equal to 745.7 watts.

1 metric horsepower is equal to 735.5 watts.

1 electrical horsepower is equal to 746 watts

1 boiler horsepower is equal to 9812.5 watts.

1 hydrololic horsepower is equal to 745.7 watts.

1 air horsepower is equal to 745.7 watts