PHYSICAL WORLD

Physical World

Physics: Physics is a branch of science which deals with physical quantities. In detail, Physics is the study of nature and phenomena occurring in nature. In the study physicists try to discover the rules or laws that are operating in nature, on the basis of observations, comparisons, experiments and analysis.

Fundamental forces in nature

In Physics there are many forces. Among those four are considered as fundamental forces. Those are

1) Gravitational force 2) Electromagnetic force

3) Strong nuclear force 4) Weak nuclear force.

1) Gravitational force:

Gravitational force is the force of mutual attraction between any two massive bodies by virtue of their masses.

Properties:

These forces are

a) very weak in nature

b) long-range forces

c) independent of medium between them

d) depends upon the product of the magnitude of the masses

e) inversely proportional to the distance between the masses

f) always along the line joining the two masses

g) only attractive.

Newton's law of gravitation formula

2) Electromagnetic force:

The force acting between any two charges at rest is called electrostatic force. The force acting between any two magnetic poles is called magnetic force. Electrostatic and magnetic forces are close interrelated. Thus the electrostatic and magnetic forces are considered as two facts of the general force known as the electromagnetic force.

Eg: If two charges are separated by a distance r then force between them

Properties:

These forces

a) between like charges repulsive and between unlike charges attractive.

b) very strong in nature

c) depends on the medium between them

d) depends upon the product of the magnitude of the charges

e) inversely proportional to the distance between the charges

3) Strong nuclear force:

These are the forces between the nucleons (small/ fundamental particles inside the nucleus)

Properties:

These forces are

a) strongest in nature

b) short-range forces

c) spin-dependent

d) charge independent

e) 100 times stronger than electromagnetic forces

4) Weak nuclear force:

These forces appear only in certain nuclear processes like beta decay where nucleus emits an electron or positron and neutrino.

Properties:

These forces

a) weak forces

b) range is up to few fermi

c) stronger than gravitational forces.