Poles and forces

A simple bar magnet has two ends where its pull is strongest: a north pole (N) and a south pole (S). On the bench the N half of each bar is red and the S half is blue.

The rule is short: like poles repel, unlike poles attract. N pushes N away, S pushes S away, and N and S pull together. Try it before reading on.

Look at the two force arrows: they are always equal in size and opposite in direction. Magnet A pushes on B exactly as hard as B pushes on A. That is Newton's third law, and it holds for magnets too.

Move the magnets closer and the arrows grow fast. Magnetic forces are strong at short range and weak far away. You will measure how fast they fade later in this world.