Sir Isaac
Newton
Sir Isaac
Newton
Physics is boring, physics is useless and a
pain in the a... 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.
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 underlying 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 preëxistent 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 Albert 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
Just send me an e-mail at fietsica@telenet.be