I wrote: On Tue, Nov 17, 2015 at 1:40 AM, <[email protected]> wrote: > > yes, but energy = force * distance. If the distance is zero, then so it the >> energy. >> > > The distance is large, as the magnet is accelerated along an arc as the > earth rotates. >
Even if this is true, it's probably irrelevant and can be ignored. But what shouldn't be neglected is the fact that the distance is zero due to subtracting forces. There is the force of the gravity of the earth, and there is the counteracting force of the magnet. If you take away the magnet, work would be done on the ferromagnetic weight as it is accelerated to the ground. It is the magnet that provides an equal amount of "work" to keep this from happening. (Perhaps the point is simply that this is not an accelerating frame of reference, which makes sense.) Eric
