"Horsepower" is a unit used to measure the power output of automobiles and other motor vehicles. It can be abbreviated as "HP." The number of physical quantities we deal with on a daily basis is so vast that it's almost impossible to list them all; temperature, force, and distance are some of the most common ones, but they barely scratch the surface.
The units of these forces (Celsius, Newton, and meter, respectively) sound pleasant to us now that we are accustomed to them. Typically, the units of physical quantities take the names of the scientists who first discovered them or made unique contributions to their respective fields. So, why is "horsepower" used to measure engine power? There's an interesting story behind the answer to this question.
It all began with a series of inventions and discoveries made by the renowned inventor James Watt, who had improved the existing steam engine to be more efficient. However, at that time, the world was accustomed to the Newcomen engine, which was the first machine to use steam. Watt's engine, along with other technical improvements, managed to produce the same amount of mechanical output using only a quarter of the fuel required by the Newcomen engine.
Watt wanted to clearly market this significant technical advantage of his design over the Newcomen engine. Marketing this obvious technical advantage was quite straightforward for those who used steam engines. He could either speak to them using a lot of "motor jargon" or simply say, "Hey, my engine does the same thing as the Newcomen engine but uses 75% less fuel!"
The issue was that not everyone was using steam engines at that time; there was still a large population that used horses for their work "mechanically." Watt then found a way to explain the advantages of his own engine to the people who relied on horses for their livelihoods.
Watt, trying to calculate how much power an average horse could produce within a certain period, eventually found that a typical workhorse could do about 33,000 foot-pounds of work per minute and maintain the same speed. One horsepower is equal to the power required to lift 550 pounds one foot in one second, which is equivalent to approximately 746 watts.
The value of horsepower was not absolute, but this was not really important for Watt or potential buyers. The only thing a load horse owner needed to know was that Watt's steam engine could do at least 5 times more work than their own load horse. So, Watt's horsepower was equivalent to at least 5 horses. Thanks to horsepower, Watt spoke in a language that the public could understand and spread the advantages of his own engine to everyone. The famous inventor's engine became one of the most valuable tools of the Industrial Revolution.
Even today, when talking about the output power of turbines, piston engines, and other machines, the term "horsepower" is still used as an additional unit.
James Watt, as known worldwide today, was truly a genius. Not only did he create a much more efficient steam engine than what existed at the time, but he also found a way to impressively market it to a people living in the past. In this process, Watt unknowingly gave the world a new unit of power that is still widely used today.
