units and measurements

Question 1

What are physical quantities?

Answer 1

Physical Quantities-

Those quantities which can be measured, or are used in physics

Question 2

What are units?

Answer 2

Units-

The standard which are chosen for measurement

Question 3

What are the different system of units ?

Answer 3

System of Units-

CGS (centimetre-gram-second)
french system

FPS (foot-pound-second)
british system

MKS (metre-kilometre-second)

Question 4

What are SI units ? What are the two types of SI units ?

Answer 4

SI Units-
> Introduced in 1960
> SI system is the metric system that is used universally as a standard for measurements.
> SI units use decimal system
> Conversion is very simple and convenient

There re two types of SI units-

1. Fundamental units
2. Derived units

Question 5

What are fundamental units?

Answer 5

Fundamental units are those units which do not depend on any other unit for their measurement. There are 7 fundamental units, and two supplementary units

Question 6

List all fundamental units and the two supplementary units

Answer 6

fundamental units

1. length (m)
2. mass (kg)
3. time (s)
4. temperature (K)
5. luminous intensity (cd) (candela)
6. electric current (A)
7. amount of substance (mol) (mole)

supplementary units

1. radian (rad)
2. steradian (sr)

Question 7

What are derived units

Answer 7

Derived units are units which are dependent on, or are derived from fundamental units for their measurement
ex- force, velocity, resistance

Question 8

What are the types of physical quantities?

Answer 8

There are three types of physical quantities-

1. Vectors
2. Scalars
3. Ratios