60. Gauss Cannon

There are 3 ball bearings stuck to a magnet in a track. A fourth ball bearing is released on the opposite side of the magnet, and is attracted to it. The ball at the other end shoots off at a much higher velocity. Where does the energy come from?

A second version of the gauss cannon is below and uses one spherical magnet which looks identical to the ball bearings. The device can first be shown without the magnet, when it acts like Newton's cradle and conserves energy. With the magnet, the end ball shoots off the end of the ramp.