Just came across this interesting and enlightening article and thought to share it with you guys. .:
Chances are you've heard
about horsepower. Just about every car ad on TV
mentions it, people talking about their cars bandy the word about and even most lawn mowers have a big sticker on them to tell you the horsepower rating. But what is horsepower, and what does the
horsepower rating mean in terms of performance?
In this article, you'll learn exactly what horsepower
is and how you can apply it to your everyday life.
The term horsepower was invented by the engineer
James Watt. Watt lived from 1736 to 1819 and is
most famous for his work on improving the
performance of steam engines. We are also reminded of him every day when we talk about 60-watt light bulbs.
The story goes that Watt was working with ponies
lifting coal at a coal mine, and he wanted a way to
talk about the power available from one of these
animals. He found that, on average, a mine pony
could do 22,000 foot-pounds of work in a minute.
He then increased that number by 50 percent and
pegged the measurement of horsepower at 33,000
foot-pounds of work in one minute. It is that arbitrary unit of measure that has made its way down through the centuries and now appears on your car, your lawn mower, your chain saw and even in some cases your vacuum cleaner.
What horsepower means is this: In Watt's
judgement, one horse can do 33,000 foot-pounds of
work every minute. So, imagine a horse raising coal
out of a coal mine as shown above. A horse exerting
1 horsepower can raise 330 pounds of coal 100 feet
in a minute, or 33 pounds of coal 1,000 feet in one
minute, or 1,000 pounds 33 feet in one minute. You
can make up whatever combination of feet and
pounds you like. As long as the product is 33,000
foot-pounds in one minute, you have a horsepower.
You can probably imagine that you would not want to load 33,000 pounds of coal in the bucket and ask the horse to move it 1 foot in a minute because the horse couldn't budge that big a load. You can probably also imagine that you would not want to put 1 pound of coal in the bucket and ask the horse to run 33,000 feet in one minute, since that translates into 375 miles per hour and horses can't run that fast.
However, if you have read How a Block and Tackle
Works, you know that with a block and tackle you can easily trade perceived weight for distance using an arrangement of pulleys. So you could create a block and tackle system that puts a comfortable amount of weight on the horse at a comfortable speed no matter how much weight is actually in the bucket.
Horsepower can be converted into other units as well.
For example:
1 horsepower is equivalent to 746 watts. So if you
took a 1-horsepower horse and put it on a treadmill,
it could operate a generator producing a continuous
746 watts.
1 horsepower (over the course of an hour) is
equivalent to 2,545 BTU (British thermal units). If
you took that 746 watts and ran it through an electric heater for an hour, it would produce 2,545 BTU (where a BTU is the amount of energy needed to raise the temperature of 1 pound of water 1 degree F).
One BTU is equal to 1,055 joules, or 252 gram-
calories or 0.252 food Calories. Presumably, a horse
producing 1 horsepower would burn 641 Calories in
one hour if it were 100-percent efficient. Source: auto.howstuffworks.com/horsepower.htm 1 Like |
