HowStuffWorks "How Horsepower Works"
[http://www.howstuffworks.com/] SUBSCRIBE Adventure Animals Auto Culture Entertainment Health Home & Garden Lifestyle Money Science Tech Video Shows Quizzes Auto Basics Tech and Transport Auto Parts & Systems Auto Racing Buying & Selling Car Models Driving & Safety Fuel Efficiency Motorcycles Trucks Under the Hood Home / Auto / Under the Hood / Engines / Engine Performance How Horsepower Works by Marshall Brain Page 1 Introduction to How Horsepower Works 2 Measuring Horsepower 3 Horsepower in High-performance Cars 4 Lots More Information Sports Car Image Gallery Alexandra Wyman/WireImage Two high-horsepower Dodge Challengers line up at the drag strip. See more sports car pictures . 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 . Next Up How Force, Power, Torque and Energy Work Engine Performance Quiz HowStuffWorks Forums: Are you afraid of your car's engine? TreeHugger.com: Top 5 Engine Technologies 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. In this article, you'll learn all about horsepower and what it means in reference to machines. Print Cite This! Close Please copy/paste the following text to properly cite this HowStuffWorks article: Brain, Marshall. "How Horsepower Works" 01 April 2000. HowStuffWorks.com.
14 August 2014. Citation & Date Feedback Page 1 Introduction to How Horsepower Works 2 Measuring Horsepower 3 Horsepower in High-performance Cars 4 Lots More Information More To Explore More Great Links Top 10 Green Driving Tips 5 Scariest Stunt Car Feats The Ultimate CarStuff Fan Quiz 5 Warning Signs You Need New Tires 10 Most Expensive Classic Cars Watch American Chopper videos >> You Might Also Like How Rotary Engines Work A rotary engine is an internal combustion engine, but it's not like the one in most cars. Learn about the unique rotary setup and how it compares performance-wise to a piston engine. Car Smarts: Diesel While diesel earned itself a bad reputation for spewing soot in the early days, improvements have made it much cleaner. Test your knowledge of all things diesel with this quiz. Popular Articles How does the intake manifold affect your engine? How is diesel fuel injection different? How does engine placement affect handling? Most Popular Most Watched Most Popular 10 Tips for Buying a Salvage Auto How Windshield Wipers Work Top 10 Alternative Fuels on the Road Right Now The Ultimate Automotive Physics Quiz 10 Amazing Car Security Systems Most Watched Understanding Cars Auto Parts & Systems Deconstructed Wrecks to Riches: Rebuilding Classic Cars Car Accident Videos Bikes, Hacks, Trikes and Choppers Don't Miss Vote: What’s the coolest fictional spacecraft? Quiz: Can you face these haunted hotels? CHECK OUT OUR PODCASTS HOWSTUFFWORKS NEWSLETTER THE LATEST AND GREATEST SUBSCRIBE HOWSTUFFWORKS Adventure Animals Auto Culture Entertainment Health Home & Garden Lifestyle Money Science Tech MORE STUFF Blogs HSW Tools RSS Maps Podcasts Quizzes Newsletters Video HSW Brazil HSW China STUFF WEBSITES BrainStuff CarStuff Fw:Thinking Stuff Mom Never Told You Stuff of Genius Stuff They Don't Want You to Know Stuff to Blow Your Mind Stuff You Missed in History Class Stuff You Should Know CUSTOMER SERVICE Advertising Contact Us Help CORPORATE About Us Careers @ HSW Privacy Policy Visitor Agreement TAKE US WITH YOU FOLLOW US Copyright © 1998-2014 HowStuffWorks, a division of InfoSpace LLC