Unit 9: Nature of Science

Class 9 Physics | Punjab Curriculum and Textbook Board Syllabus 2025

1 Science

Science is a collective knowledge about the natural phenomena, processes, and events occurring around us.

2 Branches of Science

Biological Science: The biological sciences which deals the living things. Physical Science: The physical science which is about the study of non-living things.

3 Natural Philosophy

Natural Philosophy is the study of nature that gave birth to a single discipline, now known as science.

4 Physics

Physics is the fundamental science that deals with the constituents of the universe—matter, energy, space, time, and their mutual relationships and interactions.

5 Space (Physics)

Space is the three-dimensional extent in which all objects and events occur. It provides the framework to define positions and motions of various objects under some force.

6 Time (Physics)

Time measures the sequence and duration of events. It is considered the fourth dimension.

7 Theory of relativity

Theory of relativity explains that space and time are not absolute, but are related to each other and are influenced by gravity and speed.

8 Quantum mechanics

Quantum mechanics explains the behavior of particles at the atomic and subatomic levels.

9 Mechanics

It is a study of motion and the physical effects which influence motion. It is based on Newton's laws of motion and gravitation and is often called classical mechanics.

10 Heat and Thermodynamics

It deal with the thermal energy possessed by the materials and it is used when it flows from one body to another.

11 Acoustics

It deals with the nature and physical aspects of audible sound energy.

12 Optics

It deal with the physical aspects of visible light.

13 Electromagnetism

It is the study of electromagnetic phenomenon and mutual relationship between electric current and magnetic field.

14 Quantum Mechanics

It explains the behavior of particles at the atomic and subatomic level.

15 Relativistic Mechanics

It explains how space and time are not absolute quantities but related to observer. It describes the relationship between them and how they are influenced by gravity and speed.

16 Nuclear Physics

It is the study of the properties of nuclei of the atoms.

17 Particle Physics

It is the study of subatomic particles and elementary particles which are basic building blocks of matter.

18 Astronomy

It is study of distribution of celestial bodies like planets, stars and galaxies.

19 Cosmology

It explores the large structure and evolution of the universe.

20 Solid State Physics

It is the study of some specific properties of matter in solid form.

21 Interdisciplinary Nature of Physics

Interdisciplinary nature of Physics refers to integration and interaction of Physics with various other fields of study.

22 Biophysics

Some biological systems and processes are described using the principles and technique of physics under this field of Study.

23 Medical Physics

It applies physical principles to develop techniques and technologies for health diagnosis and treatment.

24 Astrophysics

It deals with the physical properties and processes of celestial bodies and phenomena.

25 Geophysics

It applies physical principle to the study of internal structure of the Earth, its magnetic and gravitational fields, seismic activity, volcanoes, etc.

26 Climate Physics

It includes the study of physical processes in the environment, including atmospheric dynamics, climate change and weather conditions.

27 Computational Physics

It is about the use of computational techniques and methods to solve complex physical problems.

28 Interdisciplinary Research

Interdisciplinary research involves collaboration between different scientific disciplines to address complex issues and challenges.

29 Scientific Method

Scientific method is a systematic approach used to search for truth of an issue and problem solving regarding natural and physical world.

30 Steps of Scientific Method

(i) Observation: The first step in scientific method is to make observations of natural processes and to collect the data about them.
(ii) Hypothesis: On the basis of the data collected through observations or experimentation, we can develop a hypothesis.
(iii) Experiment: Experiment is an organized repeatable process which is used to test the truth of a hypothesis.
(iv) Theory: After the successful verification of an assumption and with the help of careful experimentation, it becomes a theory.
(v) Prediction: After the careful analysis of a theory we can make predictions about certain unknown aspects of nature.
(vi) Falsifiability: It is a concept introduced that suggests a theory to be considered scientific if it also makes predictions that can be tested and potentially proven false.
(vii) Law: When a theory has been tested many times and generally accepted as true, it is called a law.

31 Mass-Energy Equivalence (Einstein)

In the 20th century, Albert Einstein declared that mass and energy, the two concerns of Physics, are forms of each other.

32 Science vs. Technology vs. Engineering

Science: Physics plays a vital role being the core of each invention based on physical laws and principles.
Technology: Technology refers to the methods and techniques developed by using scientific knowledge.
Engineering: Engineering is the process of applying various technologies and scientific principles to design various instruments, tools and build things that help to meet specific needs in every walk of life.

33 Falsifiability

Falsifiability means that a scientific idea or theory can be tested to show whether it is right or wrong.

34 Laser Technology

Laser technology is based on principle of atomic physics.