"Torque" is a way of describing how hard something is
turned or twisted, in the same way we talk about "forces" as something
that pushes or pulls. If we want to move a heavy box across the floor,
we need a large force to push it. In the same way, if we want to turn a
rusty bolt we will need a large torque.
Suppose you do have a
rusty bolt that is stuck and you need to turn it. You know you will
need a large torque to do this, but how can you make this? It's easy!
It turns out that torque is the product of force and distance. In other
words, to make a large torque you need either a large force or a large
distance. To turn a rusty bolt you would put a wrench on it and push or
pull on the end of the wrench. The "force" is how hard you push or
pull, and the "distance" is how far from the bolt you are pushing or
pulling. If you push or pull far away from the bolt, which requires a
long wrench, the torque is bigger than if you push close to the bolt.
If you have a really long wrench you dont need much force to turn your
bolt, whereas if you only have a small wrench you will need to push or
pull much harder to produce the same torque. Another important
ingredient is that you push on the wrench in a direction perpendicular
to the wrench.
You may also have heard the word torque
describing the performance a car engine, for example you might read
that a certain engine produces "high torque". This means that the
engine is good at turning the wheels of the car.
I hope this helps.
If you want to learn more about forces and torques, have a look in any physics textbook.
(republished on 07/13/06)