Question

A bar magnet and a second object are hung from metal rods. The diagram below shows what happens when both objects are released.

At left, rectangular box with 2 black lines running straight down from it, each to a horizontal bar magnet with the left magnet labeled N to the left and S to the right and the right magnet unlabeled. There is a gap between the magnets. At right, a rectangular box with 2 black lines running down from it, each to a horizontal bar magnet with the left magnet labeled N to the left and S to the right and the right magnet unlabeled. There is a gap between the magnets. The left magnet hangs to the left. The right magnet hangs to the right.

Which best describes the object on the right?

an iron bar
a steel bar
a bar magnet with its north pole on the left
a bar magnet with its south pole on the left

Answer 1

A bar magnet with its south pole on the left.

Reason: the left magnet’s right end is S. The two hangers rotate away from each other, so the facing poles repel — they must be the same. Thus the other object has S on its left (i.e. a bar magnet, south pole on the left).