By Jonathan Ram, Year 13
When people go shopping, they usually want the newest, shiniest, strongest, and best overall product. This statement holds true for nearly everything, and is especially true for cars. The defining characteristics of cars are very important in consumer’s minds: the price, color, and size of the car. Consumers also tend to look at horsepower and torque, which refer to the power and overall potential output of the car’s engine. Although they are slightly different concepts, many people tend to mix the two up. This article aims to clarify the difference between the two terms.
The concept of horsepower was invented by a Scottish physicist named James Watt in the 1800s to compare the power output of steam engines to horses. As the name suggests, horsepower is just a measure of power or, in other words, the work done per unit of time. One unit of horsepower is equal to around 750 watts, meaning 750J of work (energy) in 1 second is equal to 1 horsepower. In a car, the amount of power that it can produce is an indication of how fast it can go and how fast it can accelerate. The horsepower of a car is a measure of its maximum speed: how fast the car can go, considering the mass of the car and the friction it experiences.
Although similar to horsepower, the concept of torque is slightly different, but nevertheless important when talking about vehicles. Torque is simply a force which is applied at a distance and causes rotation about an axis to happen. For example, if you take a wrench and you try to unscrew a nut or bolt, the torque that is being applied is simply the force pushing or pulling the wrench multiplied by the distance (length) of the wrench. Now, if you take a longer wrench to unscrew the same nut or bolt, you will be applying a greater torque as (torque) = (force) x (distance). Changing the length of the wrench in this analogy is equivalent to changing gears in internal combustion engines in cars. The force output of the engine is more or less the same (as the car gets the same amount of gas), and the lower the gear, the larger its radius is. Therefore, the lower the gear is, the more torque the car will produce. This is why it is very easy for a car to accelerate from a standstill to a moderate speed, because the car is in low gears and produces more torque, and it is harder for a car to accelerate from a moderate to high speed, because the car is in higher gears and produces less torque.
This article hopefully gave you a better insight into the concepts of both horsepower and torque. For more information about these concepts, I highly recommend you watch this video, and read this article.
