2. DEFINITION:-Measurement is defined as "Comparison of an
unknown quantity with some known quantity of the same kind.
PHYSICAL QUANTITY:-
I. A physical quantity is a quantity which can be measured.
For Example: length, mass, time, temperature, electric current,
light intensity, volume and many others.
II. Physical quantities have magnitude and unit.
For Example: If the height of a student is 104cm then 104 is its
magnitude and cm is the unit of measurement
MEASUREMENT
3. UNITS
• UNITS are the fixed quantities in the measurement.
• It is classified into two types.
• Standard units
• Non standard units.
4. STANDARD UNITS
• Standard units of
measurement are those that
have a fixed quantity and does
not vary from person to person
or from place to place.
• E g.. metre, kilogram, second
etc
NON - STANDARD UNITS
• Non standard units are
the units of the physical
quantities that varies
from person to person or
from place to place.
Hence it is non reliable.
• E g.. yard, fathom,
handspan etc.,
5. FOOT
The length from the
heel to the big toe of
a person is 1 foot.
FATHOM
The distance between
the tips of both
outstretched arms is 1
fathom.
6. STRIDE
The distance covered
in a step when the
legs are fully
stretched is 1 stride.
CUBIT
The distance between the tip of
the middle finger and the elbow
of a normal person is 1 cubit.
7. HANDSPAN
The width of the human hand
measured from the tip of the
thumb to the tip of the little
finger is 1 handspan.
YARD
The distance between the
chin to the tip of the
stretched arm is 1 yard.
11. SI UNITS
• In 1960, the General conference of weights and
Measures recommended that a common system should
be used all over the world. This system was called SI
system.
• SI is the abbreviation of ‘Systeme International d’unites’
in French.
• It is used uniformly all over the world for all scientific
work.
13. MULTIPLES AND SUBMULTIPLES OF UNITS
PREFIX ABBREVIATION SUBMULTIPLES/MULTIPLES
deci d Sub multiple : 1/10
centi c Sub multiple : 1/100
milli m Sub multiple : 1/1000
Kilo k Multiples : 1000
mega M Multiples : 1000000
• Multiples are used to make large measurement.
• Submultiples are used to make small measurements
14. LENGTH
• The separation between any two different
points is called length.
10 millimetre (mm) 1 centimetre (cm)
100 centimetres (cm) 1 metre (m)
1000 metre (m) 1 kilometre (m)
15. MASS
The amount of matter present in a given
substance is called mass.
1000 milligram (mg) 1 gram (g)
1000 gram (g) 1 kilogram (kg)
100 kilogram (kg) 1 quintal
10 quintal 1 metric ton
16. TIME
Time is used to measure the interval
between any two events.
60 second (s) 1 minute (min)
60 minute (min) 1 hour (h)
24 hour (h) 1 day
365 days 1 year
10 years 1 decade
10 decade 1 century = 100 years
10 centuries 1 millennium = 1000
years
17. OTHER
CONVERSIONS
• 1 mile = 1.61 km (or) 5280 ft
• 1 yard = 0.9 m (or) 3 ft
• 1 ft = 30.48 cm
• 1 inch = 2.54 cm
• 1 kg = 2.2 lb(pound)
• 1 lb = 0.45 kg
18. NEED FOR ACCURATE MEASUREMENT
• In our daily life we use measurement. For example a tailor
measures length of a cloth, a vegetable seller measures
mass of vegetables, a milkman measures volume of milk, an
architect measures area of a plot.
• In scientific work, more accuracy is needed.
• It is important to improve the methods of making
measurement.
19. Accuracy
• Exact or correct value of measurement.
• E g., a carpenter measures the length of the wood
required to make a window.
Estimation
• Estimation is a quick judgement about the
measurement or a rough value of measurement .
• E g., Adding sugar in a cup of milk needs estimation.
20. RULES TO BE FOLLOWED IN WRITING
THE SYMBOLS OF UNITS.
• Symbols are not followed by any punctuations.
• Symbols are not written in the plurals.
• The units named after scientist are not written with a
capital initial letter. Eg kelvin
• The symbols of the units named after scientist should be
written by a capital letter. Eg., K for kelvin, A for ampere.
• Small letters are used as symbols for units not derived
from a proper name. eg., m for metre.
