Force is anything, we experience in our daily life. In general words, we can define it as a physical quantity needed to push, pull, carry or throw any object, deform or break them. In real world, there are various sources from where we experience force. On the basis we categorised this forces into four major groups, which are known as fundamental forces.
1. Gravitational Force
It is the force of mutual attraction between two bodies by virtue of their masses. It is a universal force. Every body attracts each other body of the universe with this force. This force was discovered by Sir Isaac Newton.
Two bodies of masses m₁ and m₂ and separated by a distance r is given by
F = Gm₁m₂/r²
Some Basic Features Of Gravitational Force
(I) This is a universal force i.e. every object in this universe experience this force due to every other object.
(II) Motion of any satellite (artificial or natural) around the planet, motion of bodies falling to the earth, all these phenomena are governed by gravitational force.
(III) A gravitational force exists without any physical contact between acting bodies.
2. Electromagnetic Force
The force acting between two electric charges at rest is called electrostatic force.
This force was discovered by coulomb. For like charges, force is repulsive and for unlike charges force is attractive.
The magnitude of the electromagnetic force F between two point charges q₁ and q₂ separated by distance r in vacuum is given by
F = 1/4πε₀×q₁q₂/r²
Some Basic Features Of Electromagnetic Force
(I) When charges are in motion, they produce magnetic field resulting into forces on those moving charges.
(II) Electromagnetic forces do not need any physical contact or interventing medium for their existence.
(III) This force is 10³⁶ times greater than gravitational force acting between two charged particles for a fix distance.
(IV) The structure of atoms and molecules, changes during a chemical reaction, mechanical, thermal and other properties of materials. All are governed by electromagnetic forces.
(V) At microscopic level of Physics, gravitational force is dominant as compared to electromagnetic force because matter as a whole is electrically neutral due to presence of both negative and positive charge in equal quantity.
3. Strong Nuclear Force
The strong attractive force which binds together the protons and neutrons in a nucleus is called strong nuclear force.
We know that nucleus consists of protons and neutrons. Protons being positively charged could repel each other and explode the nucleus. Thus, a new force come into existence and known as strong nuclear force.
Some Basic Features Of Strong Nuclear Force
(I) This force is strongest of all fundamental forces.
(II) It is 100 times stronger than electromagnetic force in strength.
(III) This force is charge independent i.e. It acts equally between like charges or unlike charges.
(IV) The range of this forces very small i.e. about 10⁻¹⁵ m.
(V) Electrons in atoms do not experience nuclear force.
4. Weak Nuclear Force
It is the force that appears only between elementary particles involved in a nuclear process such as beta-decay of a nucleus. In beta-decay, the nucleus emits and electron and an uncharged particle called neutrino. The electron and neutrino interact which each other through a week nuclear force. This nuclear force is much stronger than the gravitational force but much weaker than strong nuclear and electromagnetic force.
Some Basic Features Of Weak Nuclear Force
(I) The range of weak nuclear force is very small of the order of 10⁻¹⁶ m.
(II) Any process involving neutrino and anti-neutrino is governed by weak nuclear force because these particles can experience only weak interaction and not the strong nuclear interaction.
(III) Weak nuclear force is 10²⁵ times stronger than the gravitational interaction.