more horsepower (defs)

Doug H wrote:

>One horsepower equals 746 watts in the same way one gallon equals
>231 in**3 or one inch equals 25.4mm. One HP will always equal
>746W or 550 ft.lb/s because it is a unit of measure.

Doug,

Yes, an arbitrarily decided unit of measure. The question HERE (in
this thread) is whether it is a GOOD unit of measure compared to the
mechanical definition. Is horsepower about power CONSUMED or power
OUTPUT? Are the two REALLY equivalent?

>Perhaps it is difficult to see how mechanical HP can be equivalent to
>electrical power. If you took Watt's horse and hitched it to a
>friction device, that device would produce heat equivalent to a
>resistive element that consumes 746 watts.

Doug,

Thank you for the comparison. Is this the reason 746 Watts was
chosen? Can you provide a link or reference? Seems like an awful lot
of variables here...

Ballendo

P.S. Thought I'd inject some definitions to this thread:

Watt-(After James Watt, Scottish inventor).A unit of electrical power
produced by a current of one ampere across a potential difference of
one volt, or a unit of power equal to one joule per second.

Joule-A unit of work or energy equal to 10,000,000 ergs, or the work
done by a force of one newton acting through a distance of one
meter.Named for James Joule, English physicist.

The metric unit of force is the Newton, defined as the force which,
if applied for one second, will cause a 1-kilogram object starting
from rest to reach a speed of 1 m/s.

And from: http://members.aol.com/jackproot/met/
The SI unit is the Watt, equal to 1 joule per second.
The foot-pound per second ( = 1.3558 W, of course)

The Horse-Power (H.P.) is worth an explanation. In the old mines, a
horse would pull a load of 150 lb. up the shaft and through a pulley
at a steady speed of 2.5 miles/hr (or 220 ft per minute) all day
long. Its power was therefore : 150 * 220 = 33 000 ft.lb/min or 550
ft.lb/sec. (Equiv. to 745.69 Watt)