Two bar magnets are held in place with their north poles facing each other. Both magnets are released at the same time. Which statement describing changes to the energy of the system is correct?

Question

Responses

Potential energy increases, and kinetic and thermal energy decrease.

Potential energy increases, kinetic energy decreases, and thermal energy increases.

Potential energy decreases, and kinetic and thermal energy increase.

Potential energy decreases, kinetic energy increases, and thermal energy decreases.

Answer 1

When two bar magnets are held in place with their north poles facing each other, they are in a state of potential energy due to the repulsive magnetic force between like poles. When the magnets are released, they will move away from each other due to the repulsion.

As they move apart, the potential energy associated with the magnetic system decreases because the magnets are getting farther away from each other. This decrease in potential energy is converted into kinetic energy as the magnets accelerate away from each other. Therefore, kinetic energy increases.

Since the magnets are moving and losing potential energy, some of this energy may also be converted into thermal energy due to friction or air resistance as they move, but this effect is not the main focus.

Considering these points, the most accurate statement is:

Potential energy decreases, kinetic energy increases, and thermal energy may increase.

However, based on the given options, the best match is:

Potential energy decreases, kinetic energy increases, and thermal energy decreases. (This is not entirely correct, as thermal energy may actually increase slightly due to movement, but it is the closest from the provided statements.)