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Force

By | Feb. 2013
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Scientists used to say that what we call nature, that is the whole universe, was made up of matter and force; but now-a-days they find that the atoms that make up the matter are really force, so that matter itself is only a form of force. But it will be convenient to use the word force in its usual sense of energy, and to give as illustrations of the forces of nature such great powers as light, heat, electricity, gravitation, and life. The study of the first four of these forces is called the science of Physics; and physicists have discovered a great deal about them. But we can only speak here of a few of the more obvious effects of these forces, especially as far as they have been found useful to man. Take the force of gravitation. The effect of gravitation is one of the most familiar experiences in everyday life, as we know when we fall down, and when we see anything that is thrown into the air fall back again to the earth. Yet no one knows exactly what this force is Isaac Newton, the great English mathematician, discovered the law of gravitation that is the rule by which this force always seems to work; but even he could not explain what it really is. All he could say was that it seemed to be a force of attraction that tends to draw masses of matter towards each other in a certain way, namely in direct proportion to their mass and in inverse proportion to the square of their distance. Hence the earth on which we live draws all smaller objects near it towards its centre, so that, as we say, everything tends to fall on to the earth; hence the sun draws the earth towards itself, and keeps it revolving round it. But for gravitation, all the things of the surface of the earth would be flung off, the earth itself would fall to pieces, and rush off in fragments into space. Men have always been familiar with lighting; but it is only in modern times that they have identified it with electricity, and found ways of producing it and making it useful to them, in such forms...

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