Learn the basics of Torque. In this article we learn what is torque, how it is used with worked examples and gears to illustrate the principle.
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Torque is the measurement of the force which causes something to rotate around a point. Think of a wrench and a nut that’s seized up. Using a small wrench it’s very hard to free the nut. Using a long wrench will make it much easier. That’s because of torque. If we use a 30cm wrench, and applied 90 newtons of force, we have 0.3 metres x 90 newtons equals 27 newton meters of torque. However, if we applied the same 90 newtons of force to a wrench that was 60 centimetres long then we would get 0.6 metres x 90N = 54N.m. So from this simple formula, we can see we have more force acting on the nut by using a longer wrench. Essentially we are using a larger circle to turn a smaller circle. By changing the size, we change the speed and the torque. A low gear provides low speed but high torque, a high gear gives high speed by low torque.
Why Do We Need Gears?
If you have ever ridden a bike, you will know it is very difficult to start peddling in a high gear. So we need to start in a low gear to get the bike moving. At a certain point our legs are spinning very fast, but we cant go any faster. So we need to change to another higher gear. Once we reach a steep hill, we need to move to a lower gear. The same with a car, we start in our lowest gear number, and work our way up as the vehicle increases in speed. Then, we change down as we drive up a hill.
Nice, but you left out pure torque.