Chronology Current Month Current Thread Current Date
[Year List] [Month List (current year)] [Date Index] [Thread Index] [Thread Prev] [Thread Next] [Date Prev] [Date Next]

[Phys-L] Re: conservation of angular momentum question



|
|
| "Torque" and "moment" are synonymous. A couple is a special
| type of torque.
|
| About any origin, there is a torque associated with each
| force. If the line of action of a force passes through the
| origin, then the torque associated with that force is zero.
|
| A couple is the net torque associated with two forces that
| are equal and opposite.

Its important to note that both external forces that constitute the
couple must be acting on the *same* object. This is why 3rd law
interaction pairs do not form a couple. They may have the same line of
action; but this makes for a triviality.

The significance is that the torque computed for a couple is independent
of the point about which you calculate the torque. Which is physically
inconsequential, but can be of calculational importance; allowing you to
choose a point about which to calculate torques that minimizes the
difficulty of the calculation.

Joel R.
_______________________________________________
Phys-L mailing list
Phys-L@electron.physics.buffalo.edu
https://www.physics.buffalo.edu/mailman/listinfo/phys-l