Physics is defined as the study of different laws of nature and their usage in various natural phenomena. Physics is studying the physical world and matter and its movement through space and time, along with connected concepts like energy and force. There are two principal kinds of approaches in Physics:

1. Unification: This method includes all the phenomena in the world in the form of a group of universal laws in various domains and conditions. The law of gravitation will be applied both on a falling apple from a tree, and the movement of planets around the sun can be considered examples. Electromagnetism laws will control every electric and magnetic phenomenon.
   
   
2. Reduction: It is a method for deriving characteristics of complex systems from the properties and interaction of their constituent parts. For example, the temperature studied under thermodynamics can also be connected to the average kinetic energy of molecules in a system (kinetic theory).

The scope of physics deals with the magnitude of physical quantities like energy, mass, etc. The scope of physics is best understood under the three disciplines Microscopic, Mesoscopic and Macroscopic phenomena. This phenomenon takes place at the molecular or atomic level. Scope of Physics covers measurement in magnitude as big as 1040m or more used to carry out the astronomical study of the universe and as small as 10-14m or less, which includes the study of electromagnetic forces, electrons, and protons.

Physics can be categorised broadly into Classical Physics and Modern Physics. Classical physics deals with macroscopic phenomena, whereas Modern physics deals with microscopic phenomena.

Physics, technology, and society are interconnected. Sometimes Physics gives rise to technology, and sometimes technology gives rise to new concepts of Physics and both benefit society. The development of technology proposes practical advancements, whereas the development of Physics helps us strengthen our understanding of the world. For example, Fields of Thermodynamics and Magnetism. The study of thermodynamics helped in the inventions of vehicles, new engines, refrigerators, blowers, etc. The invention of the Steam engine helped in the industrial revolution of European countries.

Forces that are visible or not visible to our human eyes in our daily life such as push-pull, change in length of strings and springs, physical forces, the pressure generated in fluid and gas, magnetic, electric, atomic force, intramolecular force, gravitational force, electromagnetic force, etc.

The four fundamental forces in nature are:

1. Gravity. 
2. The weak force. 
3. Electromagnetism. 
4. The strong force. 

Gravitational Force- Gravitational force is the force of attraction between two masses. Due to the gravitational force, we feel the earth is pulling us towards its centre. This type of force was first discovered by Newton. Due to the gravitational force, Earth is spinning around the Sun.

Electromagnetic Force- Electromagnetic force is the force existing between two charged particles. The electromagnetic force is responsible for chemical bonds between atoms that create molecules. Previously, scientists believed electricity and magnetism were two different concepts, but later it was discovered it is similar force. At the same time, charges in motion create magnetic force.

Strong Nuclear Force- Strong nuclear force is a force between protons and neutrons in a nucleus of an atom. This force is charge independent. Protons and Neutrons are made up of quarks.

Weak Nuclear Force- In nuclear physics and particle physics, this type of force only appears in nuclear processes such as β-decay of a nucleus. In β-decay, the nucleus will be emitting an electron and an uncharged particle known as the neutrino.

Towards Unification of Forces- The unification of forces is the idea that it's possible to view all of nature's forces as manifestations of one single, all-encompassing force. Today, scientists seek to unify this with the strong force without which the nucleus of an atom wouldn't hold together.

Physical laws are typically conclusions based on repeated scientific experiments and observations over many years and have become accepted universally within the scientific community. Physicists attempt to discover a mathematical equation or combined concept that would summarise all the facts in one.

For example, if the object falls from the height, the kinetic energy and potential energy are different, but the sum remains fixed as initial. The physical quantities that remain unchanged in a process are called conserved quantities. Some of the general conservation laws in nature include linear momentum, the laws of conservation of energy & mass, charge parity, angular momentum, etc. Some conservation laws are true for one fundamental force but not for the other.

Conservation laws have a deep connection with the symmetries of nature. Symmetries of space and time and other types of symmetries play a central role in modern theories of fundamental forces in nature.

Q1. What is a physical unit Class 11?

Ans. All the quantities in terms of which laws of physics are described and whose measurement is necessary are called physical quantities. Units are used in measuring physical quantities. For example, the kilogram unit of mass is defined as the mass of a specified block of platinum. They include Imperial units (foot, pound, second), CGS units (centimetre, gram, second), and MKS units (metre, kilogram, second).

Units

• A definite amount of a physical quantity is taken as its standard unit.
• The standard unit should be easily reproducible, internationally accepted.

It is divided into two types, fundamental units and derived units. Below is a table of the fundamental unit

S.No.	Fundamental Quantities	Fundamental Units	Symbol
1.	Length	metre	m
2.	Mass	kilogram	kg
3.	Time	second	S
4.	Temperature	kelvin	kg
5.	Electric current	ampere	A
6.	Luminous intensity	candela	cd
7.	Amount of substance	mole	mol

Q2. List out the essential concepts discussed in NCERT Solutions for Class 11 Physics Chapter.

Ans.

• Physical World
• Units and measurements
• Motion in a straight line
• Motion in a plane
• Laws of Motion
• Work energy and power
• Systems of particles and Rotational motion
• Gravitation
• Mechanical properties of solid
• Mechanical properties of the fluid
• Thermal properties of matter
• Thermodynamics
• Kinetic energy
• Oscillations
• Waves
  
  

Q3. What is the Physical World in Physics according to the Class 11 syllabus?

Ans.

The Physical World deals with the basic laws of nature and its demonstration. The analysis is done in nature that describes how the world works around us. Many discoveries and inventions are made by scientists all over the world. It is the knowledge of provable predictions about our universe. Science is a systematic approach to understanding natural phenomena. The eagerness and strong desire to learn about the world and resolve the secrets of nature led to the discovery of science. Nature science is divided into two sub-branches, one is Life science, and another is Physical science. Physical science is a branch of natural science that deals with the study of different natural phenomena based on other laws and evidence. Physics, chemistry, and earth science come under the category of physical science.