System of units.

Chapter #1:

Physics and Measurement:

Short Answer Questions.

1. What is a system of units? List the basic Si units.

SYSTEM OF UNITS:
DEFINITION:
"A complete set of units both basic and derived for all kind of physical quantities is called a system of units."
HISTORY:
In 1960 an international committee agreed on a set of definitions and standards to describe the physical quantities. The system that is established is called the system international. Befor 1960 many system of units were in practice such as:

1. British FPS system.
2. MKS system.
3. CGS system.

However with expansion of trade and the utilization of science and technology international system of units was adopted.

IMPORTANCE:

Due to the simplicity and convenience with which the units in this system are amendable to arithmetic manipulation, it is in universal use by the worlds scientific community and by most nations. The system of unit is made of three kinds of units:

• Base units.
• Derived units.
• Supplementary units.

BASIC SI UNITS:

there are seven base units for various physical quantities namely length mass time, temperature, electric current, luminous intensity and amount of substance (with special reference to the number of particles)

The names of the base units along with their symbols for the physical quantities are listed:
(Make table)