The Newton's laws are three principles proposed by the English mathematician and physicist Isaac Newton (1643 -1727 ). These postulates allow us to provide an answer to most of the problems that arise in the classic mechanics With respect to movement of bodies .
The Newton's first law is known as principle of inertia and points out that the bodies do not change their state of motion or rest if they are not applied a force , or if the result of the applied forces results null .
In other words, according to the principle of inertia a body is maintained in uniform line movement or in repose unless you receive the influence of a force. The balance appears when the result of the forces that affect it is zero.
From the principle of inertia it follows that the bodies oppose the modification of their state of motion or rest . Inertia, in fact, is such opposition. It should be remembered, on the other hand, that a force is the agent that can generate a variation in the state of the object.
In short, they are needed external forces so that a body leaves its uniform rectilinear movement or its rest. Therefore, without a boost, a friction , a friction, etc., the element in question will always maintain its constant speed, even when it is zero.
The principle of inertia reveals that, if we have a resting body (without movement), it will never move unless a force is applied. A box, to name a case, will only move if someone pushes it. A body that travels in a surface without friction, on the other hand, it will keep its constant speed for infinite time, until it is forced to brake by frictional forces or another mechanism.