torque???moment?...what r they physically??

Question

what is torque?...i know its not a force...but still in some wierd way it looks like force.....what is it?...the force that turns a body??.....if so can it still be measured in newtons...if yes y is it not force???and what really is moment?...the analog to mass in non rotating world???

Answer 1

Well without getting too much into semantics



Torque is rotational force, and is equivalent to the rotational mass*angular acceleration. The rotational form of newtons second law.



rotational mass, also known as moment of inertia, is a measure of how difficult it is to rotate an object.



conservation of momentum also holds for rotational forces, known as conservation of angular momentum.

Answer 2

The way to understand torque is to think of it as a vector in three dimensions. Pushing down (say 5 pounds) on a wrench is really acting in a 2 dimensional plane (say the wrench is turning in the xy plane upon acting down in the -y direction) but the work is being transmitted to the z direction (into the paper).



This is what that right hand rule is all about...



So torque is best understood as a Vector Product (as opposed to a scalar product). It is kind of a force conversion from the plane in which the 'wrenching' is applied to the perpendicular plane. Even a screw gun is rotating in the xy plane (but with a very Small 'level arm') but screwing in the z direction.



I think you could technically use Newtons to decribe Torque IF you convert all other forces to the new 'plane' (if that makes sense). But then the forces origianlly working in the new plane would be 'converted' to torques so it is pointless







Moments (assuming you mean moments from a statics analysis point of view as opposed to a moment of inertia) are essentially the same thing from a math point of view but I think moments 'give' more freedom to forces to act at angles other than parralell.



I think torque is a type of moment where the force is appllided in a plane parallel to the 'action'.

Answer 3

Torque is a strange thing. It is not a force, I've always found it easier to think of it as a 'force modifier', because really that is what it does. You can apply a force to an asteroid in space and make it spin, but while it is spinning no forces are acting on it, yet it continues to spin.

Answer 4

torque is angular force. It is the amount of force exerted from a radial point where Torque = distance from fulcrum * force. A unit of measure for torque is foot-pounds or newton-meters.

Answer 5

There is an excelent explanation at the link below.