Friday , 20 October 2017

# Strength and Shape

#### Strength and Shape

The strength of a substance, say in supporting a weight, depends on many factors. Pliability or its ability to bend is probably the chief factor of all. But there are other considerations which determine the strength of a substance beyond its own qualities. Shape is one of them.

Here is a simple experiment to show that shape considerably influences the strength of a substance. Make a bridge of two stout books and a piece of sheet iron. Let the centre of this, bore a hole; thread a piece of string through the hole and on the end of the string hang a weight. If the weight is sufficiently heavy (i.e., three or four pounds) it will pull the sheet of iron down from the books and the bridge will capsize.

Now take the iron and roll it into a lengthwise cylinder. Hang the same weight on it and replace it over the books. The weight is now supported quite firmly. Yet the support is exactly the same in both cases. The only differences lies in the shapes of the material.

## How does a ballpoint pen work?

The tip of a ballpoint pen, the part that writes, is very tiny metal ball …