Why Do We Use the Term ‘Horsepower’?

When you’re talking about performance automobiles, horsepower is a big part of the discussion. But the universal term isn’t reserved for racing cars and dragsters. The unit of measurement is actually used to designate relative power in everything from appliance motors putting out less than a single horsepower to the mighty 6,000-horsepower electric motors powering locomotives. Like other common measurements, such as inches, miles, fathoms, and pounds, the term horsepower has made its way into everyday usage. Have you ever wondered when the word was first used and why it is still so popular?

A New Standard

What is horsepower

Image via Flickr by Gamma Man

Technological advances sometime create conditions that have never been seen before. As these new doors open, the existing vocabulary isn’t always sufficient to describe new events, processes, and inventions. For consistency, new terms are hatched to standardize the way people talk about the technology. The concept of horsepower was launched in exactly this way, resulting from game-changing developments in steam engine technology. As engines stood ready to supplant horses as a power source, it was only natural to compare the output of the machines to that of the animals they’d come to replace. After early observers first made the correlation between the power of horses and that of machines, it is believed that an engineer named James Watt latched on to the idea in order to help promote his steam engine technology. While observing draft horses at work, Watt tried to isolate exactly how much work each horse could perform in four hours on the job. Further experimentation with a brewery horse led Watt to the conclusion the animal could produce 32,400 foot-pounds of power per minute. The figure was standardized to 33,000 in 1783, so a single horsepower represents the power required to lift 33,000 pounds one foot in one minute. Expressed another way, the value is equivalent to 550 foot-pounds per second.

A Descriptive Unit of Measure Shows its Staying Power

Despite emerging more than 200 years ago, the universal term of horsepower has not been replaced in modern vernacular. Horsepower still holds up as the best way to express engine output. And though many individuals don’t know why the word horsepower came into prominence, people understand the relative meaning of the term. Consumers have seen it used to describe the power output of blenders, garbage disposals, lawn mowers, motorcycles, cars, and almost anything capable of generating power. The familiar concept is sometimes expressed in terms of size, such as a “bigger” or “smaller” engine, but physical dimensions are not what determine horsepower. The term is strictly concerned with power output, so engineering, materials, and build quality are among the most important factors influencing horsepower ratings. Horsepower is a useful concept for comparing the relative power of cars and other consumer goods. A 1-HP garage door opener, for example, has the power to lift a larger door than a ½-HP model. And a high-horsepower car will go from 0 to 60 mph faster than one with less HP. First applied in the 1780s to express the might of steam locomotives, the word horsepower has taken its permanent place in the English language