Why Do Some Things Bend and Others Break?
When an outside force is applied to some objects, some of them will bend and others break. It is due to the fact that in some things the particles have the faculty of sticking together or hanging on to each other, and it is very difficult to break them away from each other. In such instances, as in the case of a wire, the article will bend when we apply the power to it and it will not break, because the particles which make up the wire have the faculty of hanging on to each other. A piece of glass, however, can be broken right in two by the application of no more force than was used to bend the wire, because the particles which make up the glass haven’t the faculty to hang on to each other. If you continue to bend a wire back and forth, however, at the same point, it will finally break apart, because you eventually overcome the ability of the particles in the wire to hang on to each other.
It all depends upon the hanging-on ability. Sometimes in undergoing different processes an article which will ordinarily only bend will become very brittle or breakable. A steel wire may bend but if you make a steel wire very hard it becomes brittle. On the other hand, glass is very brittle ordinarily, but if you make it very hot, you can bend it into any shape you wish, and thus the glass-worker makes different shapes to various dishes; lamp chimneys, bottles, etc., by heating glass and then bending it. When it becomes cool again, it also becomes brittle or breakable as before.