TOPIC 1: INTRODUCTION TO PHYSICS  
Introduction  
Physics is the fundamental branch of science that explores the principles  
governing the behaviour of matter and energy in the universe. Physics deals  
with very large objects like planets and very small ones like atoms.  
It also covers various of concepts, theories and principles that provide insights  
into the natural world and its interactions.  
In this chapter, you will learn the concepts, theories and principles of Physics.  
The competencies developed will enable you to apply the concepts, theories and  
principles of Physics to solve daily life problems. You will also be able to relate  
physics with other branches of natural sciences.  
Concept of Physics  
The universe is a totality of matter, energy, space, and time. The word universe  
originates from the Latin word 'universus' which means 'all or everything'.  
It can therefore be referred to as everything surrounding us; within, near, far and  
beyond our planet, solar system, and galaxy in which our solar system belongs  
(the Milky Way Galaxy). We are part of the universe.  
Science is the major tool for studying and exploring the universe. It begins with  
inquiries such as what is the universe? What is its origin? What makes up the  
universe? How does it change with time? Why does the sky look blue? And why  
does iron turn red when heated? To answer such questions, the applications of  
theories, principles and laws of science are required.  
Physics falls under a broad category of natural science, which is divided into three  
main branches, namely physics, chemistry, and biology. Physics is the branch of  
science which deals with the study of matter, energy and their  
interactions.  
The word physics originated from the Greek word 'Physikos' which means  
'nature'. Physics involves the study of physical and natural phenomena around  
us. Examples of these phenomena are the occurrence of eclipses, causes of sunset  
and sunrise, the formation of the rainbow, and volcanic eruption. Figure By  
definition, Physics is the branch of science that deals with the study of matter,  
energy and the mutual interactions between them.  
A person who studies physics is known as a Physicist.  
In Physics, matter is studied in relation to its motion, as well as space and time.  
Matter is defined as any substance which has mass and occupies space. Physics  
as a subject uses concepts like force, energy, and mass to explain different  
phenomena.  
Energy, for example, may take the form of heat, light, or electricity. Among the  
most important forms of energy today is electricity which can be generated in  
many ways including waterfalls and combustion of natural gas.  
BRANCHES OF PHYSICS  
Physics is divided into several branches, each focusing on different aspects of the  
universe. Some of the major branches of physics are:  
1. Mechanics  
Mechanics is the branch of physics that deals with objects that are either stationary  
or in motion, the influence of forces acting on them and their impacts. Under this  
branch, aspects like linear, circular, and oscillatory motions of objects as well as fluids  
and their impacts are studied.  
2. Heat  
Heat is one among the forms of energy. Heat can be transferred from one point to  
another by either conduction, convection or radiation. This branch of physics  
describes the phenomena of matter when heat energy is supplied to it. These  
phenomena include the expansion of matter, changes of states of matter, and the  
anomalous expansion of water.  
3. Light  
Light is a form of energy that travels in a straight line. There are two types of light  
sources: Natural and artificial. The Sun is the primary or main source of natural light.  
We see different objects with the aid of light. Our eyes enable us to see objects when  
light falls on them.  
4. Electromagnetism  
Electromagnetism is the branch of physics that deals with the interaction between  
electric and magnetic fields. It has a wide range of applications in our daily life,  
including generation of electricity and fabrication of motors. Life could be difficult  
without electricity.  
5. Astronomy  
Astronomy deals with the study of the universe (cosmos) and everything contained in  
it. The word astronomy originates from two Greek words, 'astron' which means 'star'  
and 'nomos' which means 'laws. Therefore, Astronomy referred to as the study of laws  
of stars. Astronomy seeks to answer inquiries such as how celestial objects like moons,  
planets, stars, and galaxies originate and change with time.  
6. Geophysics  
Geophysics is the branch of physics that deals with physical processes and physical  
properties of the Earth and its surroundings. It speculates the interior and exterior  
structure of the earth in terms of physical and chemical properties.  
7. Electronics  
Electronics is the basis of modern technology. It involves the study of circuits that  
are made of semiconductor components like, diode, transistor, and integrated  
circuits. Most of communication devices are made of semiconductor materials.  
Examples of devices that use the principles of electronics are television, radio.  
Light Emitting Diode (LED) lamps, mobile phones, cameras, printers, and  
computers.  
8. Physics of the atom  
This is a branch of physics which deals with the behaviour of particles that make up  
the atom and accompanying energy.  
We learn about radiation which is emitted by the atom during disintegration and how  
we can protect ourselves from harmful radiation.  
Connection between Physics and other disciplines  
Physics relates to many subjects in terms of either direct applications or the principles  
governing the working of instruments used in a given subject. Physics is closely related  
to chemistry, biology and mathematics. Physics is also related to earth sciences such  
as geology and meteorology. The relationships between physics and other subjects  
are discussed below.  
1
Physics and chemistry  
Chemistry principles are used to produce pesticides and insecticides (see Figure  
below), perfumes, and fertilizers. Then, physics principles are applied in  
packaging them so that they can be released in a controlled manner from  
compressed cylinders or sprays. Also, chemists use equipment designed and  
constructed using physics principles to achieve extraction of chemicals  
2
Physics and biology  
A number of instruments such as microscopes used in biology are designed and  
constructed using physics principles. Processes such as photosynthesis, conversion of  
matter into energy, and even the transfer of heat used in biology can be well explained  
by using laws of physics.  
3
Physics and mathematics  
Mathematics is a working tool of almost all disciplines. All branches of mathematics  
for instance, algebra, trigonometry, and vectors are applied to study physics. More  
often mathematical relations are used in expressing physics concepts. For instance,  
force, F is directly proportional to extension, e.  
This concept can be expressed mathematically as; F=ke where k is a constant of  
proportionality.  
4
Physics and meteorology  
Meteorology deals with the study of weather and climate. Meteorologists use an  
instrument like rain gauge in Figure (a) which is designed and constructed using the  
principles of physics to measure rainfall. A wind vane in Figure (b) uses physics  
principles to measure direction of the wind.  
5
Physics and astronomy  
Astronomy deals with the study of objects that compose the physical universe.  
It involves the study of stars, planets, satellites, nebulae, galaxies as well as the  
distribution of matter and energy in space and time.  
Due to its complexity, astronomy uses principles, theories and laws of natural  
science, engineering, technology and mathematics (STEM). Therefore, physics  
plays a crucial role in astronomy. For example, the laws of planets and other  
objects present in the solar system are shown in Figure below.  
IMPORTANCE OF STUDYING PHYSICS (Why do we study physics  
Generally, physics helps us to understand nature. The following are examples of its  
importance.  
a) The study of physics enables a person to answer questions about the physical  
properties of matter.  
b) Physics helps to answer questions like why some materials are attracted by  
magnets while others are not, why the sky looks blue, and why clouds look white.  
c) The study of physics enables us to acquire skills that are required in  
different professions such as engineering, technology, teaching, and  
architecture.  
d) The study of physics enables us to acquire knowledge and skills that are  
applied in designing and constructing different items which are useful in our  
daily lives. These include simple machines such as pulleys inclined planes,  
and complex ones like bicycles, escalators, and bulldozers.  
e) Physics is fun. It helps to understand the applications of physics principles in  
sports and games.