A metal bar (mass, $m$) is placed across two very long, parallel metal rails (separated by a distance, $L$) that are connceted through a resistor ($R$). A constant magnetic field ($B_0$) points into the page. You give the metal bar a quick flick away in the direction away from the resistor. You notice that the bar comes to a stop after some time traveling down the rails. Explain how this happens. Sketch the velocity of the bar as a function of time.

The power dissipated in a resistor is $P=I^2R$. Given the initial flick of the metal bar, show that energy is conserved in this strange circuit system.

How does all this fit with your knowledge about magnetic forces and work?