Question

In addition to friction, if the iron beads roll up and down the rails, this also causes energy loss. What should we do to prevent the kinetic energy of the iron beads from escaping into the vibrations of the rails?

Answer 1

The vibration in the rails is caused due to the interaction of uneven surfaces of the rail and the iron bead.

To make the explanation easier take the bead as a car and the rail as humps on roads...when the car passes over the humps, then some kinetic energy of the car is transferred through vibration. In order to prevent that, one must either remove the humps from the road or apply some concrete to reconstruct the road so that the car can pass over smoothly without loss of kinetic energy.

Similarly in the above case one must apply a good lubricant over the rough rails so that instead of exhibiting pure rolling motion, the bead can slide over the rail without much loss of KE through vibrations.