UNIT OF MEASUREMENT

1.NEED FOR MEASUREMENTS

 

In ancients times measurements carried out differed from person to person.Each person, in his/her measurements used a common unit.Cubit, step, hath, bitta, etc. were a few examples of such measurements for length. Similar conventions were used for time and mass . With the growth of trade and industry, people felt the need for a common standard and accurate measurements.With expanding frontiers of science and technology and developments of communication between countries the need for standardization and acceptance of those standards for measurements all over the world has now become a necessity.

The role of measurement in science, engineering and technology is exemplified by lord Kelvin, a leading physicist of the 19’th century.

“When you can measure what you are talking about and express it in numbers, you know something about it, but when you can’t your knowledge is of a meager and unsatisfactory kind, it may be the beginning of knowledge but you have scarcely in your thoughts advanced to the stage of a science,whatever the matter may be.”

PHYSICAL QUANTITIES

Physics is a branch of science which deals with nature and nature phenomena.We observe a nature phenomenon and try to express it as a relationship among the quantities involved.The quantities which are involved in a nature phenomenon and which can be observed and measured, are called physical quantities.

Some examples of a physical quantities are mass of an object, length of a plank, volume of a liquid, speed of car, current in a wire, force applied, atmospheric pressure etc. We will encounter these and other physical quantities and study phenomena involving them.