Principle of relativity
From Simple English Wikipedia, the free encyclopedia
The principle of relativity of Galileo says "Is impossible by mechanical means to say whether we move or stay at rest".
This principle is just taken from observation. If for example we are travelling by plane at constant speed we can walk through the corridor noticing nothing special.
From a practical point of view, this means that the Newton equations are valid in all the inertial systems, which means those at rest or those moving with constant speed respect one considered at rest.
Therefore, if we want to observe an effect in a moving system at constant speed, we can apply the Newton laws directly. If the moving system accelerates (or we accelerate respect it, like observing the stars from the earth) then we will have to introduce fictious forces to compensate this effect.
This fictious forces are called centrifuge force and coriolis force.
