By Jaan Kalda (TalTech).
The center of a non-magnetic metal ball with radius R is at the origin; the ball is in a homogeneous magnetic field B that is parallel to the x-axis. The ball rotates with an angular speed \omega around the x-axis. At x=L, y=z=0, there is another identical metal ball that does not rotate. Find the interaction force between the two balls, assuming that L\gg R and R\ll \sqrt{\rho/\mu\omega}, where \rho denotes the ball’s resistivity and \mu is the permeability.
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