If there are 745 watts for every horsepower how many horses would it take to power a single hundred watt light bulb? explanation .

(100 watts) x (1 horse / 746 watts) = (100/746) horse = 0.134 horse

This calculation assumes that a horse can produce power continuously at the rate of one horsepower.

But wait ! This MAY be a trick question.

100 watts is 0.134 of 1 horsepower. That much is true.

But the question asked "How many horses would it take ?". The answer to THAT question is "1.00 horse".

The reason is simple:

==> IF a horse always produces power at the rate of one horsepower (746 watts),

and

==> IF you want to hire only enough horses to produce 100 watts,

then

==> as a city boy, you might think that you need to slice off 0.134 of a horse. But horses don't work that way. They only work in multiples of a whole horse, and they have a very strong union. If you put 0.134 of a horse to work, the power output is zero !

To get any amount of power UP TO 746 watts, you need a whole horse.

conduction, convection, radiation