Basic Fundamental Forces in Nature

               1. Gravitational Force

The gravitational force is the force of the mutual attraction between any two objects by virtue of their masses. Gravitational force is the utmost basic fundamental force in nature. The gravitational force mainly acts between two or more bodies of greater masses. The gravitational force is the force of mutual attraction between any two objects by virtue of their masses. It is a universal force. Every object in this universe experiences this force due to every other object in the universe. All objects on the earth, for example, experience the force 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, of course, the motion of bodies falling to the earth. The value of gravitation on the earth is 9.8 m/sec². It plays a key role in the large-scale phenomena of the universe, such as formation and evolution of stars, galaxies and galactic clusters. There is a formula to find the gravitational force(F) between two body of mass m1 and m2 is 

                       F = G m1 m2 / r²

where, r is the distance between the radius of given two bodies and G is universal gravitation constant whose value is 6.67×10^-11. If there is no gravitational force on the earth there would be no gravity and all the objects on this earth will float. As, we know there is no gravity on the earth all the objects on the moon floats in the open space and there is no atmosphere due to no gravitational force. 

Properties of Gravitational forces are:

1. Gravitational forces are universal attractive forces. 

2. These are the weakest forces in nature. 

3. They operates over very long distance especially when the bodies are massive. 

4. Gravitational forces obey inverse square law. 

5. Gravitational forces are central forces. 

6. Gravitational forces are conservative forces. 

 

       2. Electromagnetic Force

Electromagnetic force is the force between charged particles or between two ions. In the simpler case when charges are at rest, the force is given by Coulomb’s law : attractive for unlike charges and repulsive for like charges. Charges in a motion produce magnetic effects and a magnetic field gives rise to electromagnetic force on a moving charge. Electric and magnetic effects are, in general, inseparable – hence the name electromagnetic force. Like the gravitational force, electromagnetic force acts over large distances and does not need any intervening medium. It is enormously strong compared to gravity. The electric force between two protons, for example, is 1036 times the gravitational force between them, for any fixed distance. Matter, as we know, consists of elementary charged constituents like electrons and protons. Since the electromagnetic force is so much stronger than the gravitational force, it dominates all phenomena at atomic and molecular scales. (The other two forces, as we shall see, operate only at nuclear scales.) Thus it is mainly the electromagnetic force that governs the structure of atoms and molecules, the dynamics of chemical reactions and the mechanical, thermal and other properties of materials. It underlies the macroscopic forces like ‘tension’, ‘friction’, ‘normal force’, ‘spring force’, etc. Gravity is always attractive, while electromagnetic force can be attractive or repulsive. Another way of putting it is that mass comes only in one variety (there is no negative mass), but charge comes in two varieties : positive and negative charge. This is what makes all the difference. Matter is mostly electrically neutral (net charge is zero). Thus, electric force is largely zero and gravitational force dominates terrestrial phenomena. Electric force manifests itself in atmosphere where the atoms are ionised and that leads to lightning.

Properties of Electromagnetic Force  are:

1. These forces may be attractive or repulsive. 

2. They also obeys inverse square law. 

3. They operates over distance which are not very long. 

4. They are also central forces. 

5. Thy are also  conservative forces

 

        3. Strong Nuclear Force

The force that binds the neutrons and proton together in a nucleus are called the strong nuclear forces.  It is evident that without some attractive force, a nucleus will be unstable due to the electric repulsion between its protons. This attractive force cannot be gravitational since force of gravity is negligible compared to the electric force. A new basic force must, therefore, be invoked. The strong nuclear force is the strongest of all fundamental forces, about 100 times the electromagnetic force in strength. It is charge-independent and acts equally between a proton and a proton, a neutron and a neutron, and a proton and a neutron. Its range is, however, extremely small, of about nuclear dimensions (10–15m). It is responsible for the stability of nuclei. The electron, it must be noted, does not experience this force. The protons and neutrons are built out of still more elementary constituents called quarks. 

 Properties of Nuclear Force are:    

 1. Nuclear Forces are the strongest forces in nature. 

2. Nuclear forces have the shortest distance. 

3. Nuclear force do not depend on charge on the nucleon. 

4. Nuclear force do not obeys inverse square law. 

5. Nuclear forces are non- conservative forces.

  

 

          4. Weak Nuclear Force

The weak nuclear forces are the forces of interaction between elementary particles of short times. The weak nuclear force appears only in certain nuclear processes such as the β-decay of a nucleus. In β-decay, the nucleus emits an electron and an uncharged particle called neutrino. The weak nuclear force is not as weak as the gravitational force, but much weaker than the strong nuclear and electromagnetic forces. The range of weak nuclear force is exceedingly small, of the order of 10–16 m. 

Properties of weak nuclear forces  are:

1. The weak nuclear forces are 10^25 times stronger than the gravitational force. 

2. The weak nuclear forces exists between the leptons and lepton, mesons ans leptons, leptons and mesons, etc. 

 

   5. Towards Unification of Forces

By unification of forces,we mean that there exits a relationship between the various forces of nature. The unification is a basic quest in physics. Great advances in physics often amount to unification of different theories and domains. A lot of efforts have been made towards the unification of different forces of physic. Some of them are: 

(1). Newton unified terrestrial and celestial domains under a common law of gravitation. 

(2). Oersted and Faraday showed that electric and magnetic phenomena are in general inseparable. 

(3).Maxwell unified electromagnetism and optics with the discovery that light is an electromagnetic wave. 

(4). Einstein attempted to unify gravity and electromagnetism but could not succeed in this venture.

 But this did not deter physicists from zealously pursuing the goal of unification of forces. Recent decades have seen much progress on this front. The electromagnetic and the weak nuclear force have now been unified and are seen as aspects of a single ‘electro-weak’ force. What this unification actually means cannot be explained here. Attempts have been (and are being) made to unify the electro-weak and the strong force and even to unify the gravitational force with the rest of the fundamental forces. Many of these ideas are still speculative and inconclusive.