Law of conservation of energy

[elitewarr]

Homework Statement

An interaction occurs when two strong magnets are held stationary with the north pole of one pushed against the north pole of the other. On letting go, the magnets spring apart. It is apparent that the kinetic energy of the magnets has increased. Explain how the law of conservation of momentum applies in this case.

Homework Equations

The Attempt at a Solution

What I think is that the total momentum in the system remains the same and a magnetic repulsion occurs on both bodies, as well as contact force, which is an action-reaction pair. Is it wrong? Thank you.

 

[anathema]

I would like to clarify and expand on your understanding of the law of conservation of momentum in this scenario. The law of conservation of momentum states that in a closed system, the total momentum before an event must be equal to the total momentum after the event. In this case, the two magnets make up a closed system since there are no external forces acting on them.

When the magnets are held stationary with their north poles pushed against each other, they have equal and opposite momentums, resulting in a total momentum of zero. When the magnets are released, they experience a repulsive force due to their magnetic fields. This force causes them to accelerate away from each other, increasing their velocities and therefore their momentums. However, the total momentum of the system remains the same, as the increase in one magnet's momentum is balanced by the decrease in the other's. This is in accordance with the law of conservation of momentum.

It is also important to note that while the kinetic energy of the magnets has increased, the total energy of the system remains the same. This is because the magnets are not receiving any external energy, but rather converting their potential energy (due to their position) into kinetic energy.

In summary, the law of conservation of momentum applies in this case as the total momentum of the system remains constant, despite the change in velocity and kinetic energy of the magnets. This showcases the fundamental principle that momentum is conserved in all interactions within a closed system.