Physics Basics and fundamentals
Chapter-1
Physical World
Physics-Physics is a basic discipline in the cate- gory of Natural Sciences, which also includes other discipline like Chemistry and Biology.
The word Physics comes from a greek word mean- ing nature. Its Sanskrit equivalent is Bhautika that is used to refer to the physical world.
Reduchionism-A related effort to derive the properties of a bigger, more complex system, from the properties and interactions of its constituent simpler parts. This approach is called Reduchionism and is at the heart of physics. aloudas sT (vi)
Classical Physics-Classical Physics microscopic deals mainy with phenomena and includes subjects like Mechanics, Eletrodynamics, Optics and Thermodynamics.
Fundamental Forces in Nature-Force is needed to push, carry or throw objects, deform or break them. At the present stage of our understanding we belive there are four fundamental forces in nature,
which are described in brief below:
(i) The Gravitational force-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 experiences this force due to every other object in the universe.
(ii) The Electromagnetic force- Electromagnetic force is the force between charged particles.
(iii) The Strong Nuclear force-The strong nuclear force binds protons and nutrons in a nucleus.
(iv) The Weak Nuclear force-The weak nucle- ar force appears only in certain nuclear process- es such as the B-decay of a nucleus.
The weak nuclear force is not as weak as the gravitational force, but much weaker than the strong nuclear and electromagnetic force.
Neutrino-In ẞ-decay, the nucleus emits an 8 electron and an uncharged particle called Neutrino.
Conservation Laws-Motion under an external conservative force is the total mechanical energy, i.e., the sum of kinetic and potential energy of a body is at constant.
Mass-Energy equivalance-A consequence of Einstein’s relativity. The mass of a bond system like a nucleus is not exactly equal to the sum of the masses of its constituents, the protons and neutrons. It is slightly less, by an amount equal to the buinding energy (B.E.) divided by the square of the speed of light.
Mass of a band system = sum of the masses of its constituents – B.E./c².