Page 34 - Physics

Physics for Secondary Schools

may also be used. For example, if Table 2.1: Fundamental physical quantities and
the length of a playground is 100 their SI units
m, ‘100’ is the number part while Physical quantity SI unit Unit symbol
‘m’ is the unit part. Therefore, a Length metre m
meaningful measurement must Mass kilogramme kg
have both a number and a unit. Time second s

Electric current ampere A
A complete measurement that
includes both number and unit Temperature kelvin K
parts is called a measurement of Amount of substance mole mol
a physical quantity. For example, Luminous intensity candela cd
the measurement of 100 km, Vector and scalar quanti ti es
2 kg or 10 s.
The physical quantities can further be classifi ed
Physical quantity into either vector or scalar quantities.

A physical quantity is any Vector quantities
measurable quantity. Physical Vector quantities are those quantities that have
quantities are divided into two both magnitude and direction. Examples of vector
categories, namely fundamental quantities are force, displacement, velocity and
physical quantities and derived momentum.

physical quantities.
Scalar quantities
Fundamental physical Scalar quantities are those quantities that have

quantities magnitude but have no direction. Examples of scalar
Fundamental physical quantities quantities are mass, distance, time, density, volume,
are quantities of measurement pressure, speed, electric current, work, energy, and
which cannot be expressed in power.
terms of other quantities. These For example, consider a car traveling at a speed
include; length, mass, time, of 100 kilometres per hour North. This describes
temperature, amount of substance, the velocity of the car which is 100 kilometres per
electric current and luminous hour in the North direction. Velocity is a vector
intensity. Among the measured quantity. However, if the intention is to describe

fundamental physical quantities only the speed of the car and not the direction,
mass, length and time are the most the statement could be simply that the car is
common. Table 2.1 shows the travelling at 100 kilometre per hour. Speed is a
fundamental physical quantities scalar quantity. Table 2.2 gives some of the vector
and their respective SI units. and scalar quantities.

28
Student’s Book Form One

Physics Form 1 Final.indd 28 16/10/2024 20:55