Sir Issac Newton was the first one to give an exact definition for force.
“Force is the external agency applied on a body to change its state of rest and motion”. There are four basic forces in nature. They are gravitational force. electromagnetic force, strong nuclear force and weak nuclear force.
Gravitational force
It is the force between any two objects in the universe. It is an attractive force by virtue of their masses. By Newton’s law of gravitation. the gravitational force is directly proportional to the product of the masses and inversely proportional to the square of the distance between them. Gravitational force is the weakest force among the fundamental forces of nature but has the greatest large-scale impact on the universe. Unlike the other forces, gravity works universally on all matter and energy, and is universally attractive.
Electromagnetic force
It is the force between charged particles such as the force between two electrons, or the force between two current carrying wires. It is attractive for unlike charges and repulsive for like charges. The electromagnetic force obeys inverse square law. It is very strong compared to the gravitational force. It is the combination of electrostatic and magnetic forces.
Strong nuclear force
It is the strongest of all the basic forces of nature. It. however. has the shortest range. of the order of 10-15 m. This force holds the protons and neutrons together in the nucleus of an atom.
Weak nuclear force
Weak nuclear force is important in certain types of nuclear process such as 13-decay. This force is not as weak as the gravitational force.
