The direction of the magnetic force depends on the direction of the magnetic field of the ball and the magnetic field induced in the block. The magnetic field of the ball doesn't change direction, but the direction of the field in the block depends on the direction of the induced current, and the direction of the induced current depends on the direction of motion of the ball, which does change. So you wind up with a force that always opposes motion, similar to friction. (It is a non-conservative force, which means that, like friction, energy is lost in the form of heating the ball and block.)
It occurs to me that I didn't actually put the specs of the video in the post, so I'll leave them as a comment: The video was shot at 240 frames per second using a Chronos camera that a former colleague bought some years back. It's monochrome, which is why everything looks grey.
Well apparently I am one of your eight readers. I thought the videos were outstanding. And I wouldn't say "enormous dork," but maybe "total nerd." There's a huge difference, just ask my wife.
Unintuitive in that the force slows down the ball whether it is approaching the copper or moving away from it (if I am interpreting that right).
The direction of the magnetic force depends on the direction of the magnetic field of the ball and the magnetic field induced in the block. The magnetic field of the ball doesn't change direction, but the direction of the field in the block depends on the direction of the induced current, and the direction of the induced current depends on the direction of motion of the ball, which does change. So you wind up with a force that always opposes motion, similar to friction. (It is a non-conservative force, which means that, like friction, energy is lost in the form of heating the ball and block.)
It occurs to me that I didn't actually put the specs of the video in the post, so I'll leave them as a comment: The video was shot at 240 frames per second using a Chronos camera that a former colleague bought some years back. It's monochrome, which is why everything looks grey.
So cool.
Jim Baggott, and now Chad Orzel. Wow, I only just found out. My lucky day. And eddy currents, to boot.
Well apparently I am one of your eight readers. I thought the videos were outstanding. And I wouldn't say "enormous dork," but maybe "total nerd." There's a huge difference, just ask my wife.