# What is Torque?

1. Jul 8, 2006

### LifeIsGreat

Can anyone give me a 'simple' explanation of torque? And how is it measured? Or tell me best place to find this info?

Thanks!

2. Jul 8, 2006

### arildno

$$\vec{r}\times\vec{F}$$

3. Jul 8, 2006

### LifeIsGreat

lol. Thank you arildno! :-)

Sadly that helps not one bit as I am not an engineering student, but I guess the thought was there! I am working my way through Wikipedia so sure I'll get there soon.

4. Jul 8, 2006

5. Jul 8, 2006

### arildno

Okay, a bit more then:
The torque a force produces upon an object with respect to some point is directly related to how strongly the object will rotate about the point.

6. Jul 8, 2006

### LifeIsGreat

Thank you both. I think it's getting my head around the idea that "how strongly" the object rotates about the point is a combination of how "fast" and with how much "force". Wish I was a real scientist...

7. Jul 9, 2006

### Rumpelstiltzkin

Fast? Don't you mean distance?

Actually there are lots of real-world examples you can think about to get the idea about torque. For instance, consider a door. Notice that the doorknob is always as far as possible from the hinge (which is the axis of rotation). What happens if the doorknob is very near to the hinge? Does it make it easier or more difficult to open or close the door?

Direction of the force matters too. As someone mentioned, torque is the cross product of the displacement vector and force. What if both of these vectors are parallel? Work it out, then consider this: what if you apply a force to the door towards the hinge? Does it affect the rotation?