# Magnets and Conservation Laws

Q:
On magnets and their not-connection to gravitational forces, suppose you has two very strong magnets with exactly the same weight and power, a tube with friction-less inner surface (only to guide the magnets on their drop, air resistance still applies) and a building high enough for the magnets to reach their terminal velocity. Now, you drop the first magnet and shortly, the second magnet. They are released at calculated time that their magnetic fields will interfere with each other. Given they can both attract and repel each other with the same force, the question is a: if they're attracting each other mid-fall, one magnet (the later) will be decelerated while the other one (the first) will get accelerated. The reverse will happen if they rejects each other. Let's forget that in the case of attraction, both magnets will fuse and focus on the second case where the magnets will continually repel each other in the tube. Will this break the law of momentum conservation or does the magnetic forces works as potential energy?
- Rathurue (age ??)
Indonesia
A:

The magnets will obey both momentum and energy conservation laws.  Let's forget about the gravity- all the essential behavior is present whether or not they're falling. One magnet pushes the other down, the other pushes this one up. The forces are equal and opposite. So the momentum changes are equal and opposite. Momentum is conserved.  There is energy stored in the magnetic fields. That energy becomes less as the magnets push apart, supplying the kinetic energy for their motions.

Gravity just adds another force, between the Earth and the magnets. It also obeys the conservations laws, for similar reasons.

Mike W.

(published on 06/12/2016)

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