A weak object will be made of a material that easily bends, breaks or stretches. It may be weak because the material has been used incorrectly so that it is too thin, or too long for its job, or it may simply be that the material will fail easily.

An object may be quite strong if it is pushed in one way and weak if pushed in another. For example, concrete is very strong when it is under a large weight, and so is used for buildings. But in an earthquake, the concrete is shaken from side to side, and concrete is a brittle material, which means it quickly breaks. This is why buildings made of concrete must have rods of steel inside them. Steel is a material that will bend in an earthquake, but not break.