PHYSICS
PHYSICAL QUANTITIES AND MEASUREMENTS
Grade 9 | Topic 1
BRANCHES OF PHYSICS
MECHANICS
It is the study of motion of objects, its causes and effects.
HEAT
It deals with the nature of heat, modes of transfer and effects of heat.
SOUND
It deals with the physical aspects of sound waves, their production, properties and
applications.
LIGHT (OPTICS)
It is the study of physical aspects of light, its properties, working and use of optical
instruments.
It is the study of the charges at rest and in motion, their effects and their relationship
with magnetism.
ELECTRICITY AND MAGNETISM
ATOMIC PHYSICS
It is the study of the structure and properties of atoms.
NUCLEAR PHYSICS
It deals with the properties and behaviour of nuclei and the particles within the nuclei.
PLASMA PHYSICS
It is the study of production, properties of the ionic state of matter - the fourth state of
matter.
GEOPHYSICS
It is the study of the internal structure of the Earth.
SI UNITS
PHYSICAL QUANTITIES
All measurable quantities are called
physical quantities such as length, mass,
time and temperature.
BASE
DERIVED
QUANTITIES
QUANTITIES
There are seven
Those physical
physical
quantities which are
quantities which expressed
form the
in terms of base
foundation for
quantities are called
other physical
the derived
quantities.
quantities.
BASE UNITS
DERIVED UNITS
QUANTITY
UNIT
QUANTITY
UNIT
LENGTH
MASS
TIME
ELECTRIC CURRENT
INTENSITY OF LIGHT
TEMPERATURE
METRE (m)
KILOGRAM(kg)
SECOND (s)
AMPERE (A)
CANDELA (cd)
KELVIN (K)
SPEED
ACCELERATION
VOLUME
FORCE
PRESSURE
DENSITY
ms−1
ms−2
m3
kg ms −2
N m−2
kg m−3
AMOUNT OF A
SUBSTANCE
MOLE (mol)
CHARGE
As
PREFIXES
PREFIXES
SCIENTIFIC NOTATION
STANDARD FORM
PREFIX
SYMBOL
MULTIPLIER
PREFIX
SYMBOL
MULTIPLIER
exa
E
1018
deci
E
10−1
peta
P
1015
centi
P
10−2
tera
T
1012
mili
T
10−3
giga
G
109
micro
G
10−6
In scientific notation a
number is expressed as
some power of ten
multiplied by a number
between 1 and 10.
mega
M
106
nano
M
10−9
0.00045 s is 4.5 × 10−𝟒 s
kilo
k
103
pico
k
10−12
hecto
h
102
femto
h
10−15
deca
da
101
atto
da
10−18
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PHYSICAL QUANTITIES AND MEASUREMENTS
Grade 9 | Topic 1
MEASURING INSTRUMENTS
LEAST COUNT
The smallest measurement an instrument can make
MEASURING INSTRUMENTS FOR LENGTH
METRE RULE
MEASURING
TAPE
It is one metre long which is equal to 100 centimetres. Each centimetre (cm) is divided into 10 small
divisions called millimetre (mm). Least count: 1 mm.
A measuring tape consists of a thin and long strip of cotton, metal or plastic generally 10 m, 20 m, 50 m
or 100 m long.
1.
Slide the jaws against the object
2.
Read the main scale where it lines
up with the zero of the Vernier
VERNIER
CALLIPERS
scale.
3.
Read the Vernier scale and
multiply it with 0.01.
4.
Add the numbers together.
Least count = 0.01 cm
1. Slide the spindle against the object
2.
Read the main scale where it lines
up with the zero of the circular
MICROMETER
SCREW GAUGE
scale.
3.
Read the circular scale and
multiply it with 0.01.
4.
Add the numbers together.
Least count = 0.01 mm
RULES TO FIND THE SIGNIFICANT DIGITS IN A MEASUREMENT
1.
Digits other than zero are always significant.
2. Zeros between significant digits are also significant.
3.
Final zero or zeros after decimal are significant.
4. Zeros used for spacing the decimal point are not
significant. Here zeros are placeholders only
OTHER MEASURING INSTRUMENTS
MECHANICAL
MASS MEASURING INSTRUMENTS
least count = 0.1 s or 100 ms
BEAM BALANCE
least count = 0.1 g or 100 mg
DIGITAL STOPWATCH
least count = 0.01 s. or 10 ms
PHYSICAL BALANCE
least count = 0.01 g. ot 10 mg
MEASURING CYLINDER
least count = 0.001 L or 1 mL
ELECTRONIC BALANCE
least count = 0.001 g or 1 mg
STOPWATCH
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