# Homework Help: Find the net torque about an axis through O

1. Dec 15, 2005

### jesuslovesu

Last edited by a moderator: May 2, 2017
2. Dec 15, 2005

### andrewchang

if the force is going through O, and you set the axis of rotation at O, then there is no net torque. (the radius is zero)

3. Dec 17, 2005

### mukundpa

r*sin(angle) is the perpendicular distance of the force vector from the axis of rotation.

4. Dec 17, 2005

### vaishakh

Please provide me a magnifying lens, my specs don't help me much!!!
Anyway, for beginners write the force in vector form as well as the vector r which is the vector joining the point with respect to which torque is measured to the point at which force is applied. Here the torque is defined as the croos product of vector r to vector f

5. Dec 17, 2005

### mukundpa

beware! dont give pressur to your eyes. r is zero here. you can't see it.

6. Dec 17, 2005

### Astronuc

Staff Emeritus
Yeah, from the diagram given, it looks as though the force is applied at O, so there is no net torque.

7. Dec 17, 2005

### andrewchang

trick question, i guess? if i were taking a test and i saw that, i wouldn't be too happy. =P