Posted by: Mike Myers (mike.myers@bellnexxia.com) on Thu Apr 24 13:12:10 2003

Jack,

I notice you differentiate forces applied from counter-rotating hands (you call torque) vs forces applied from the full rotating hand path (CHP):

“With the aid of high-speed cameras, motion detectors, pressure sensors and a motion-study computer, it was found that there were two forces acting on the bat that generate bat-head acceleration (gravity is not supplied by the batter). One force transferred the body’s rotational energy by the angular displacement of the hands (termed - a circular-hand-path). The second force that accelerates the bat-head was torque (causing an object to rotate by forces applied from opposing direction). In the baseball swing, torque is mainly applied to the bat by the push/pull effect of the hands with a minimal amount supplied by wrist action.”

This can be a source of confusion to anyone unfamiliar with your full discussion.

Note: torque is a net force applied at 90 degrees to the axis of rotation. There is no requirement how this net force manifest i.e. two forces from opposing directions, as you suggest. This is why both forces you have identified are, in fact, torque examples.

As the long as the object changed its angular speed, torque has been applied. For example, if you pull a lever, you have applied torque to the lever, although there is only one point of application.

Regards,
Mike.