Fundamental Forces In Nature

We all have an intuitive notion of force in our experience force is  needed to push carry or throw objects deform or break them. We also experience the impact of forces on us,like when a moving objects hits us or were in a merry -go- round going from this intuitive notion to the proper scientific concepts of force is not a trivial matter.Early thinkers like Aristotle had wrong ideas about it .the correct notion of forces was arrived at by Isaac Newton in famous laws of motion. He also gave an explicit form for the force of gravitational attraction between two bodies we shall learn theses matters in substitutes or subsequently chapters.

                    In the macroscopic world ,besides the gravitational force we counter several kinds of forces (muscular forces  contact forces ) between bodies ,friction the forces are exerted by compressed or elongated springs and taut springs and ropes the forces of buoyancy and viscous force when solids are in contact with forces due to present of pressure of fluid the force due to surface tension of a liquid and so on .There are also forces involving charged  and magnetic bodies.In microscopic domain again.We  have electric  and magnetic forces, nuclear forces involving protons and neutrons inter atomic and inter molecular forces.

                   A great insight of the twentieth century physics is that these different forces occurring in different contexts actually arise from only a small number of fundamental forces in nature to the attraction /repulsion between the neighbouring atoms of spring when the spring is elongated \compressed this net attraction\repulsion can be traced to the sum of electric forces between the charged constituents of the atoms.

                 In principle this means that the laws for "derived "forces (such  as spring force friction ) are not independent of the laws of fundamental forces in nature .The origin of these derived forces is however very complex.At  the present stage of our understanding  we know of four fundamental forces in nature which are described in brief.

Gravitational Force:- The gravitational force is the force mutual attraction between any two objects by virtue of their masses.It is a universal force every objects experiences this forces due to every other objects in the universe .All objects on the earth experience the forces of gravity due to the earth..In particular gravity governs the motion of the moon and artificial satellites around the earth motion of the earth and planets around the sun and the motion of bodies falling to the earth it plays a key roles in the large scale phenomena of the universe such as formation of stars ,galaxies and galactic clusters.


Electromagnetic Force:- Electromagnetic force is the force between charged particle in the simple case when charges are at rest the force is given by Coulomb's law attractive for unlike charged repulsive for like charges.Charges in motion produce magnetic effects and a magnetic field gives rise to a force on moving charges. Electric and magnetic effects are in general inseparable hence the name electro magnetic force like the gravitational force electro magnetic force acts over large distances and does not need any intervening medium.It is enormously strong compared to gravity.