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 below shows examples of phenomena described by Physics.
➢ 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.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
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
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