Introduction to Physics - Part I

The word ìscienceì comes from a Latin word scientica, which means knowledge. Its present use is for systematic and exact knowledge. Physics is that branch of science which mostly encompasses the study of matter and energy. Physics is an exact science with mathematics forming its basic foundation. The word ìphysicsî is derived from a Greek word meaning physical or natural things.  Scientific observation and experimentation lead the way to principles or theory which again have to be tested and then accepted. This cycle leads to the established laws of Physics. From over thousands of years mankind has wondered about the sun and the stars, about the phases of the moon, eclipses of the sun and the moon, seasons, etc. From here grew the rudiments of observations and data taking, interpreting the data and then formulating a mathematical background that predicted the next cycle. Physicists try to understand how and why things behave the way they do and which underlying principles are at play.      

After mathematics, Physics is the most fundamental of all sciences. Physical laws are important in all the branches of science like biology, chemistry, engineering, etc. Many scientists have contributed to laying the foundations of Physics. Starting from Aristotle  (384- 322 BC) to Archimedes (287-212 BC) to, Galileo (1578-1657), Newton (1642-1727) in the 17^th century to Einstein, Feynman and others up to  the present century, understanding of Physics has become more deeper and thorough. There are many branches of Physics, but broadly it is classified as Classical Physics and Modern Physics (Physical laws or principles discovered before the 20^th century and after the 20^th century respectively.)  

The following table depicts a few branches of Physics.

What we will study in this chapter : 

1. System of Units
2. Fundamental, derived and supplementary units 

1. System of Units 

Measurement of any physical quantity depends on a standard. The basic quantity of the standard  is known as a unit. An actual measurement would be a fixed multiple of the unit. The multiple is called the magnitude of the unit. For example, if we decide unit length to be 1 meter, and if a length of the side of the table is 1.5 meters then magnitude of the measurement is 1.5.  

A standard unit once decided is unchangeable. Internationally a standard system of units has been agreed upon and is strictly followed by everyone. This system is called the S.I. units (Standard International). Calibrations used for measurement have to be standardized so that they remain constant, under normal everyday lives. If this was not done, then there would be chaos in the world as everyoneís measurement would be different!!

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