Posted by: ray porco () on Tue May 25 21:12:14 2004

>>> jack, with your busy schedule and all, i think you overlooked a question i asked you recently...i'll repeat it:
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> > > > > upon reflection i think teacherman made a valid point...if a boxer delivers a blow to the opponent's face, is that torque?
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> > > > > i understand your point, which was that even though the bottom hand is "stationary" rather than actually moving in the opposite direction, this can result in two forces acting in opposition to each other...but is that torque?...if not, what do you call it?...standing on the ground creates two forces acting against each other, pushing your hand against the wall results in two forces acting in opposition, but i don't think any of us call that "torque".....
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> > > > > Hi grc
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> > > > > It can get confusing, can’t it? – Torque is a measure of turning power applied to an object that determines its rate of angular displacement. To induce rotation requires forces being applied to the object from opposing directions. Basically, the amount of torque applied depends on two key factors. (1) The vectored amount of the forces applied. (2) The length of the fulcrum arm between the two forces. Note: grc, you can apply much more torque to a nut with a longer wrench than a short one because of the fulcrum arm length.
> > > > >
> > > > > In order to answer your questions regarding the ‘wall’, there is an important factor to keep in mind. – Regardless of the amount of forces applied, as the length of the fulcrum arm (distance between two forces) approaches zero, torque approaches zero. In other words, two directly opposing forces generate zero torque.
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> > > > > When you push your hand against the wall, the wall pushes directly back with the same force. Therefore, no torque was applied to the wall.
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> > > > > Jack Mankin
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> > > > Two key points that I think you should note:
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> > > > 1. Torque can be applied in only one direction to induce rotation. If you place a wrench on a nut, you can rotate the nut by applying force (in only one direction) to the handle of the wrench.
> > > >
> > > > 2. Torque can be applied in a direction other than 90 degrees to the lever arm. Torque can be computed this way adding sin/cosin.
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> > > > ray porco
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> > >
> > > Hi Ray
> > >
> > > "Torque can be applied in only one direction to induce rotation". (good point)
> > >
> > > "If you place a wrench on a nut, you can rotate the nut by applying force (in only one direction) to the handle of the wrench."
> > >
> > > True, but the wrench itself applies a force couple or couples to the nut.
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> > > "Torque can be applied in a direction other than 90 degrees to the lever arm. Torque can be computed this way adding sin/cosin."
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> > > Torque is only the perpindicular component, any other force other than 90 degrees cannot cause rotation, it could be a compressive,shear,tensile, etc. force, but will not cause rotation.
> > > Using sin/cosin you can find the torque component and the other type of force component depending on the angle of application.
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> > Enloe,
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> > A force does not have to be applied perpendicularly to a wrench to make a nut rotate. A force applied to a wrench that is not perpendicular to the wrench will produce less torque but it will still produce torque and still produce rotation of the nut.
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> >
> > ray porco
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> Hi ray
>
> I agree the nut will rotate, but you have to resolve the forces mathmatically, the perpindicular component is causing rotation (torque), the parallel component (2d) is causing compression or tension (force). The closer to a 90 degree application line the more torque.
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> >


Enloe,

Compression:
What your saying is that if the direction (line) of the force passes through the pivot point (axis) [parallel to the wrench] then the torque is zero (the lever arm is zero).

Is that what your saying?

ray porco