Measurements

Question 1

Physical Quantity

Answer 1

Any quantity that can be measured is called a physical quantity

Question 2

Fundamental Units

Answer 2

Fundamental units: can neither be derived from one another nor can they be broken.
e.g. – Length, mass, time, electric current, temperature, luminous intensity and
amount of substance.

Question 3

Derived Units

Answer 3

Derived units: are collections, combination of one or more fundamental units.
e.g. Area, volume, density, speed, velocity, acceleration

Question 4

Least Count of an Instrument

Answer 4

Least count of an instrument: It is the smallest measurement that can be
made accurately using an instrument.

Question 5

Avoiding Reading Errors

Answer 5

When using the metre rule, position your eye directly above the markings and
perpendicular to the scale to avoid parallax errors.
By taking several readings and taking the average, you will minimise reading
errors.

Question 6

Time Period

Answer 6

The time required for one complete oscillation is called its
time period.
S.I. units = second (s)

Question 7

The Frequency

Answer 7

The number of complete oscillations made by the pendulum in one second is called its frequency.
S.I. units = hertz (Hz)

Question 8

Mass

Answer 8

MASS is defined as the quantity of matter contained in a body
Its SI unit: kilogram (Kg)

Question 9

Volume

Answer 9

VOLUME is defined as the space occupied by matter

Its SI unit: cubic metre (m3)

Question 10

Archimedes Principle

Answer 10

When a body is wholly or partially immersed in a in liquid, it experiences an apparent loss in weight.

Weight of the liquid displaced = Upthrust of the body in the liquid

Question 11

Law of Floatation

Answer 11

Weight of the liquid displaced = Weight of the floating body