What is the magnitude of the normal force of the table on the lower magnet?

[tascja]

Homework Statement

What is the magnitude of the normal force of the table on the lower magnet?
(so there is a table with a magnet on top and below its surface)

Homework Equations

The Attempt at a Solution

So i was wondering if someone could help me figure out all of the forces acting on the magnet to find the normal force. So far:

- weight of the table (down)
- weight of the lower magnet (down)
and so i don't really understand what will oppose these forces.. the force from the magnet on the top of the table?

thanks :)

 

[Vuldoraq]

Try drawing an overall diagram of the situation, then draw a free body diagram for the lower magnet. Is the table resting on a surface? Or is it suspended, being help in place by the two magnets?

In either case there should only be three forces you need to take into account, and two of them will be related to the third.

The normal force is the contact 'repulsion' between surfaces that prevents objects passing through each-other.

 

[nlightner]

The normal force is the perpendicular force exerted by a surface on an object in contact with it. In this scenario, the normal force of the table on the lower magnet would be equal in magnitude and opposite in direction to the weight of the magnet. This is due to Newton's third law which states that for every action, there is an equal and opposite reaction. Since the weight of the magnet is pulling down on the table, the table exerts a normal force on the magnet in the upward direction to counteract it. Therefore, the magnitude of the normal force of the table on the lower magnet would be equal to the weight of the magnet.