Monthly Archives: March 2014
37.IF MOLECULES MOVE, WHY CAN’T WE SEE THINGS CHANGE?
If molecules are in constant motion at terrific speeds, and this is taking place in everything — even a piece of wood — why can’t we see things changing shape?
A molecule is the smallest bit of a substance that can exist and still keep the properties of the whole. For example a molecule of sugar (sucrose) is the smallest bit of sugar that would still have the taste, color, form, solubility, and other qualities of sugar. If you divided it any more, it would no longer be sugar.
36.HOW DO THEY MEASURE A RAINFALL?
Rainfall is now being measured in most parts of the world by means of an instrument called a rain gauge. The gauge of the United States Weather Bureau is shaped like a hollow tube closed at the lower end, with a funnel in the top.
This gauge is placed in an unsheltered place, and a graduated scale shows exactly how much rain has fallen in it. The Weather Bureau says that there has been an inch of rainfall if enough rain has fallen to make a sheet of water an inch deep over a given area.
35.DOES THE AIR HAVE WEIGHT?
Most of us think of air as being “nothing,” but air is definitely “something,” if it is matter made up of certain gases. A gas does not have a definite size or shape, but it takes up space.
The great ocean of air that surrounds the earth and extends for many miles upward is attracted and held to the earth by gravity. Thus air has weight. And since air is everywhere about us, it adds weight to every object it fills. For example, there is a small amount of air in a volley ball. If you were to weigh two such balls, with the air let out of one of them, you would find it’s lighter than the other.
