Question

Two donut-shaped magnets are stacked on top of each other with a wooden dowel in the center. The south poles of the magnets are facing each other. Once the upper magnet is released, it accelerates downward and stops 1 cm above the lower magnet. How does the energy stored in the magnetic field change? (1 point)
Responses

Some of the energy stored is converted into kinetic and thermal energy.
Some of the energy stored is converted into kinetic and thermal energy.

All of the energy stored is converted into kinetic, thermal, and gravitational energy.
All of the energy stored is converted into kinetic, thermal, and gravitational energy.

All of the energy stored is converted into kinetic and thermal energy.
All of the energy stored is converted into kinetic and thermal energy.

Some of the energy stored is converted into kinetic, thermal, and gravitational energy.

Answer 1

The magnetic energy increases. As the top magnet falls it does work against the repulsive magnetic force, so part of the lost gravitational potential energy is stored in the magnetic field; some of the energy goes briefly into kinetic energy and is then dissipated as heat/sound, but the net magnetic-field energy after settling is larger than before.