Sir Isaac Newton

Physics is boring, physics is useless and a pain in the bottom for every student. Well, you'd  better change your mind because almost all you ever do is ruled by physics.
How fast can you run? Swim? cycle? How far can you throw things such as stones, javelin? How good are you at football? How is the flight of a boomerang?  All this is highly dependent on the laws of physics.

Of course, if you are a donkey physics will not make a full bred wining horse out of you, but it will help you  to understand the subtleties of your chosen sport, to avoid doing stupid things or setting unreasonable goals, and to achieve the best possible results.



About equations

Equations have a bad reputation because they seem to be made for the happy few that understand them. However consider them simply as a short way of expressing otherwise long sentences.
Take the following expression: "Any object that is submitted to an external force will acquire an acceleration that is proportional to this force, and the coefficient of proportionality is called the mass of the object"

Now simply replace this sentence by the equation  F = m x a

It seems to me that the equation is much simpler as long as we remember that F represent the force, m is the mass, and a is the acceleration.

The use of equations is necessary if we want to numerically verify things and this is exactly what we pretend to do. However if you really dislike equations and mathematics, just forget about it, and only read the text. Hopefully you can still understand the explanations.

About physical laws

Common laws and physical laws are two quite different things. Common laws are made by politicians who want to organise society according to their views and convictions. Everybody is sensed to follow these rules, and being punished if they don't.
Physical laws are not man-made. They are
preŽxistent and discovered through painstaking research and observation of the natural phenomena. After testing a certain relation between cause and effect for a 1000 times we will suppose that the same relation will hold when we do the test next time, and we will call this a law of physics. This law is then a way of predicting the future. Of course, if we deliberately ignore this law we may also be punished. If we say "I can fly" and we jump of a high tower, we may be punished severely by the law of universal gravitation.
A physical law can not be invalid for a long time because one single result or test on the contrary will almost immediately lead to changing or generalising the law. Sir Isaac Newton formulated the law of universal attraction between masses around 1685. In its original form this law stood for almost 250 years, until A
lbert Einstein formulated the theory of general relativity. Since then it is known that masses also attract light, eventually leading to the existence of black holes. Is Newton now invalid? No, because in normal, or earthly conditions Einstein's law still says exactly  the same as Newton's

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