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I've seen the other posts on this question, but unfortunately I'm still having difficulty understanding the meaning of the direction of the torque vector. It makes intuitive sense that the magnitude of the torque exerted on an object is dependent on the length of the lever arm and the angle between the lever arm and the applied force.

What I don't understand is what the direction of the torque vector is describing. How can I relate the direction of the torque vector to a real world example (that is not an example involving a wrench + screw and the screw "unscrewing" in the direction of the torque...which doesn't give me any more of an intuition on what torque means).

Thanks!

BeginnersMindTruly
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  • Is your problem that the torque is out of the plane of the radius vector and force, or with the polarity of the torque in that direction? For the first, think about a gyroscope-the torque is in the direction of the axis of rotation. For the second, it is convention. – Ross Millikan Jun 18 '14 at 20:44
  • Thanks, my problem is as you mentioned. The torque is out of the plane of the radius vector and the force. When I think, for example, about a wrench and a screw, the fact that the direction of the torque is out of the plane is a bit confusing because I can't relate it to anything I can see or feel or imagine in that system. I'll look into your gyroscope example, thank you! – BeginnersMindTruly Jun 19 '14 at 19:59

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Did you notice the relationship between the angular velocity vector and the torque vector? If you apply a torque, you change angular momentum. The easiest case - starting with an object at rest - shows you that the angular momentum vector points in the same direction as the torque vector.

What is more interesting of course is that these things are additive - but the basis of the convention should be obvious from the above.

Floris
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