Base Quantities
LESSON 1 The physical quantities which are used as the basis
for the measurement and can’t be derived from other
physical quantities.
Understanding Physics There are five base quantities as shown in the
following table:
The study of the laws that determine the structure of
the universe with reference to the matter and energy
of which it consists.
The study was divided into separated fields; heat , the Base Symbol Unit name Unit Measured
quantity Abbreviation by
properties of matter, light, sound ,wave, electricity,
magnetism, mechanics, nuclear physics etc. Length
In physics , there is the need to make careful
observations, precise and accurate measurements. Mass
Understanding natural phenomena and observing
everyday objects such as a table, a mirror etc and Time
discuss how they are related to physics concepts has
always been a central aim of physics. Temperature
The roots of all science are firmly based in
experiment. Of course , mastering scientific skills Current
applying scientific knowledge must be the important
thing to learn physics.
Derived Quantities
The physical quantities which were derived from base
Physical Quantities
quantities by multiplication operation or division
Physics is based on measurement. We discover
operation or both
physics by learning how to measure the quantities
that are involved in physics and we call its as
There are three examples for derived quantities as
physical quantities.
shown in the following table.
Derived Symbol In term of Derived unit Unit
The meaning of Physical Quantities quantity the base Abbreviation
Physical quantities are quantities that can be quantities
Area
measured.
Examples of physical quantities are length, mass, Velocity
time, weight, pressure, current and force.
Density
A physical quantity is a property ascribed to
phenomena, objects, or substances that be
quantified.
Example are:
(i) Frequency of oscillation – frequency is the
quantity and oscillation is the phenomenon
(ii) Length of a wooden block – Length is the
quantity and the wooden block is an object
(iii) Density of water – density is the quantity and the
water is the substance
There are two types of the physical quantities,
• Base quantities
• Derived quantities
1

Example 1
Solution
State the following derived quantities in terms of the
base quantities.
(a) Acceleration
(Hint: Acceleration = change of velocity )
time
(b) Momentum
(Hint : Momentum = mass x velocity )
Solution
Example 2
State the base units for the following derived
quantities:
(a) Force
Scalar and Vector quantities
(Hint : Force = mass x acceleration )
A scalar is any quantity with size (magnitude) but
without specified direction.
(b) Impulse
Examples of scalar quantities include mass, time,
(Hint : Impulse = change of momentum)
length, temperature, energy, work, speed and
pressure.
(c) Work
(Hint : Work = force x displacement)
A vector is any quantity with size (magnitude) and
specified direction.
Examples of vector quantities are displacement,
weight, force, velocity, acceleration and momentum.
2

TUTORIAL 1
1 Which one of the following is not a base
7 Which one of the following pairs of derived
quantity?
quantities is true?
A B
Length Weight
A Work and mass
C D
Current Time
B Force and current
C Pressure and temperature
2 Which one of the following is not a base
D Weight and potential difference
unit?
8 Which of the following physical quantities is a
A B
Celsius Ampere
base quantity
C D
Kilogram Second
A The weight of an astronaut on the Moon’s
3 All derived quantities can be derived from base
surface is 10 N.
quantities by
B The velocity of a cyclist rides a bicycle is
70 km h-1
A addition operation or subtraction
C The perimeter of a field is 380 m
operation
D The power of a lamp is 60 W.
B addition operation or subtraction
operation or both
9 Which one of the base quantities is not involve
C multiplication operation or division
in acceleration?
operation
D multiplication operation or division
A Length
operation or both
B Mass
C Time
4 The S.I. base unit for mass is
10 Which one of the following apparatus is not
A B
gram miligram
be used to measure the density of a metal
C D
kilogram mikrogram
cube?
5 Which one of the base quantities is not involve
A Ruler
in force?
B Stop watch
C Triple beam balance
A B
Length Time
C Temperature D Mass
11 Which one of the following derived quantities
contains length and time only?
6 Which of the derived quantities is the
combination of a base quantities only?
A B
Velocity Momentum
B D
Force Pressure
A Force
B Volume
C Acceleration
3

A B
kg 2 m kg - 2 m
C D
kg m 2 kg m - 2
E kg 2 m 2
17 The period of oscillation for an inertial balance
12 is given by
Which one of the following is true?
T2= km
Physical Type of S.I. Unit
where
quantity physical
T = The period of oscillation and the unit is
quantity
s,
A Momentum Derived Kg m s-2
m = Mass and the unit is kg
quantity
k = constant
B Temperature Base quantity o C
C Work Derived kg m 2 s -2
The units of k are
quantity
D Area m2
Base
A B
kg s2 kg- 1 s 2
quantity
C kg s D kg- 2 s-1
13 The kinetic energy of a moving object is given
E kg2 s
by
E=½mv2
18 Which of the following quantity is a scalar
where m = mass and v = velocity. The number
quantity.
of the base quantities involve in the kinetic
energy ,E is or are
A B
Weight Volume
C D
Force Acceleration
A 1
B 2 19 Which of the following quantity is a vector
C 3 quantity.
14 Which of the following pairs of physical A B
Work Power
quantities and S.I. units is true? C D
Velocity Distance
Physical S.I. unit 20 Which one of the following pairs of vector
quantity quantities is true?
A Area foot squared A Impulse and area
B Weight Kilogram B Power and pressure
C Power Joules per minute C Weight and velocity
D Density Kilograms per
metre cubed 21 (a) The current flows through a metal
conductor is defined by the equation
15 Which one of the following is true?
current = charge
A The S.I. units of charge is A s time
B The S.I. units of volume is cm 3
C The S.I. units of velocity is km j - 1 Based on the equation, which of the
D The S.I. units of acceleration is cm s- 2 quantities above are
16 A physical quantity is given by
M=¾ed2 (i) base quantities
where the unit of e is unit kilogram and the unit
of d is metre. The units of M are .......................................................
(ii) derived quantities
4

....................................................... ………………………………………….
(b) The S.I. units of F, m ,M and R
(b) What are the S.I.units of charge?
...............................................................
The S.I. units of G
(c)
22 The power of a student to run up a stair is given
by the equation
Power = force X displacement
time
(a) State the base quantities contain
in the equation above.
....................................................................
(b) State the power in term of base quantities.
....................................................................
20 The Newton’s law of universal gravitation state,
the gravitational attraction force, F is directly
proportional to the product of the mass ,m and
M of two bodies and inversely proportional to
the square of distance ,R between them.
The law is given by the equation
F=GmM
R2
Based on the equation,
(a) give one example of
(i) the base quantities
…………………………………………..
(ii) the derived quantities.
…………………………………………..
(iii) the vector quantities
5