When talking about cars, enthusiasts often mention torque, horsepower, and other words you may have heard in physics class but never understood. Car lovers understand the jargon behind vehicle performance, but the average driver may have no idea what it means. Let’s take a look under the hood and learn more about torque, including foot-pounds and foot-pounds.
torque is rotational
Along with horsepower, torque is a primary measure of a car’s powertrain performance. JD Power explains the term clearly and concisely:
“Torque measures the twisting force, or force, of an engine or motor. That feeling of being pushed back in your seat when you hit the gas? That’s even. Illustrated using a non-automotive example, when opening a jar, torque is the effort with which you loosen the cap.”
Another image: think about opening a door. You instinctively push on the side farthest from the hinges. If you try to push the door on the side closest to the hinges, you will need to apply much more force to open the door. Because people generally prefer to apply less force, the door handle is installed further away from the hinges.
According to Khan Academy, torque can be static or dynamic. The static type does not produce angular acceleration. You are applying a static torque when you push the door open because it does not rotate on its hinges despite the force you apply. Pedaling a bike at a constant speed is also applying static torque because the bike is not accelerating. On the other hand, dynamic torque can be seen in a racing car accelerating off the starting line. It is producing an angular acceleration of the wheels as the car speeds up.
So now that you have the general idea, let’s review foot-pounds and foot-pounds.
It would be easy to assume that “foot-pounds” and “foot-pounds” are interchangeable. The truth is that they are not synonyms. They are separate and distinct units of measure. They can be converted to each other, but that would require some complicated math.
Foot-pounds is a unit of torque and a vector measurement created by one pound of force acting on a one-foot lever, EngineLabs explains. You’ll see the plural form of the term, “pound-feet,” abbreviated in the car’s performance specifications as 250 pound-feet of torque.
However, foot-pounds is “a measurement of work,” adds EngineLabs. “Work is the measure of force over a given distance. So, a foot-pound force (ft-lbf or simply ft-lb) is the energy required to move a one-pound object one linear foot.”
Both foot-pounds and foot-pounds have a force component (pounds) and a displacement component (feet), but they measure two different things.
What is the difference between torque and horsepower?
“Torque measurement is expressed in foot-pounds and represents how much torque is at play,” explains Edmunds. “If you can imagine a plumber’s socket wrench attached to a rusty drain pipe, torque is the force required to twist that pipe.”
Torque moves your car at lower speeds, and the amount of torque also determines how fast your vehicle can jump off a line from a standstill. Interestingly, once your car is moving, torque becomes less important and horsepower must take over to maintain higher speeds.
Horsepower is an easier term to understand when it comes to vehicles. You can imagine horses racing across the plains, but horsepower simply equates to the amount of energy needed to do 33,000 foot-pounds of work in one minute. We use horsepower to measure the ability of an engine or motor to produce power at higher speeds. You’ll see the term abbreviated as “hp” after a number, such as a 300-hp motor.
Once again, JD Power explains the difference between the two words best: “Simply put, torque gets you going, while horsepower keeps you going.”
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