In reply to Eric Walker's message of Sat, 14 Nov 2015 17:56:05 -0600: Hi, >On Sat, Nov 14, 2015 at 5:13 PM, David Roberson <[email protected]> wrote: > >Overall, this appears to be an example of a torque being applied to a >> flywheel that causes its angular momentum and angular energy to change with >> time. I do not see the analogy with the permanent magnet since that case >> is representative of a force being applied to a system that is not being >> accelerated in any manner. >> > >The analogy is a strained one. It's an example of using energy that exists >in the form of angular momentum in order to produce a linear force on a >mass to counteract another force that is already present. If one were to >attempt to apply the analogy to the case of the permanent magnet, no doubt >erroneously, the electrons in the permanent magnet would be the flywheel, >and their angular momentum would be used to produce a force to counteract >the force of gravity needed to keep a ferromagnetic weight above the >ground. There's hand waving everywhere in attempting to apply this analogy. > >In the case of the permanent magnet, the ferromagnetic weight is constantly >being accelerated away from the magnet by the force of gravity. (Assume >the magnet is attached to a rigid body.)
yes, but energy = force * distance. If the distance is zero, then so it the energy. Regards, Robin van Spaandonk http://rvanspaa.freehostia.com/project.html
