physical quantity that characterizes the measure, which act on the body or other bodies of the field is called a force.According to Newton's second law, the acceleration that gets the body is directly proportional to the force acting on it.Accordingly, to change the speed of the body, it is necessary to act on force.So true is the statement that the forces of nature are a source of any movement.
inertial reference system
forces in nature is a vector quantity, meaning they have a magnitude and direction.Two forces can only be considered as identical when they have the same module, and their directions are the same.
If the body is not affected by the forces, and in the case where the geometric sum of the forces acting on a given body (this amount is often referred resultant of all forces) is zero, the body is either remains at rest or continues to move in onedirection at a constant speed (i.e., coasting).This expression is valid for inertial reference systems.The existence of such systems is postulated Newton's first law.In nature, these systems do not have, but they are a convenient mathematical model.However, often in solving practical problems frame of reference associated with the earth, it can be considered the inertial.
Earth - inertial and non-inertial reference
In particular, when the construction work, the calculation of the motion of cars and swimming transport the assumption that the earth - an inertial reference system, it is enough to with the necessary practical solutions to problems of precisionto describe the force.
In nature, there are also tasks that do not allow such an assumption.In particular, this applies to space projects.At start up it rocket strictly due to the Earth's rotation carries visible movement not only along the vertical and in the horizontal direction against the rotation of the Earth.In this movement manifested non-inertial reference frame connected with our planet.
Physically, do not act on the rocket forces, diverting it.However, to describe the use of the missile which is inertia.These forces do not exist physically, but the assumption that their existence makes it possible to introduce non-inertial system inertial.In other words, when calculating rocket trajectories believe that the reference system "Earth" is inertial, but a rocket some force acts in the horizontal direction.This force is called the Coriolis force.In nature, its effect is noticeable in the case of bodies moving at a certain height with respect to the planet for a fairly long time or at high speed.So, consider it not only describing the motion of rockets and satellites, but also in the calculation of motion artillery shells, aircraft, etc.
Nature interactions
All the forces of nature on the nature of their origin are four fundamental interactions (electromagnetic, gravitational, weak and strong).The macrocosm is only noticeable effect of gravitational and electromagnetic forces.The weak and strong interactions affect the processes occurring in atomic nuclei and subatomic particles.
The most common example of gravitational interaction is the force of attraction.It is a force with which the Earth acts on the surrounding body.
electromagnetic forces, in addition to the obvious examples include elastic all related to the interaction of the pressure that the body have on each other.Accordingly, a force of nature like gravity (the force with which the body acts on the suspension or support), has an electromagnetic nature.
