Physical World Revision Notes: Natural Science, Laws, Physics

Physics deals with the study of basic laws of nature and their manifestation in different phenomena. Physics can be defined as understanding basic principles, the force applied, the matter around us, and many more. The chapter Physical World will deal with topics like

• Natural science (A branch of science that deals with the description, prediction, and understanding of natural phenomena)
• Fundamental forces of nature (gravitational force, strong nuclear force, electromagnetic force, and weaker nuclear force)
• Conserved quantities
• Conservation laws (law of conservation of masses, law of conservation of energy, law of conservation of angular momentum, and law of conservation of linear momentum), and many more.

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Science

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The term Science originated from the Latin word ‘Scientia’ which means ‘to know. Science can be defined as a systematic way to understand natural phenomena in as much detail and depth as possible and use the knowledge to modify, predict, and control the phenomena. Science is all about exploring and experimenting. The scientific method includes –

• Systematic observation
• Controlled experiments
• Quantitative and qualitative reasoning
• Mathematical modeling
• Prediction and verification of different theories
• Speculations

Physical World- Branches

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Natural Science

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Natural science helps us to understand the working of the world and universe. It can be defined as a branch of science that deals with the description, prediction, and understanding of natural phenomena.

It is divided into two main branches –

• Life Science, also known as Biology
• Physical Science i.e. also subdivided into physics, chemistry, earth science, and astronomy.

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Physics

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Physics deals with the study of basic laws of nature and their manifestation in different phenomena. It can also be defined as the study of the physical world and matter and its movement through space and time along with topics like energy, force, and many more.

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Fundamental Forces in Nature

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The fundamental forces of nature are visible in our daily life such as friction, muscular, forces, fluid and gas pressure, electricity, and many more.

• Gravitational Force: The force of mutual attraction between any two objects because of their masses is known as gravitational force. It keeps all the celestial bodies revolving in their orbits.
• Strong Nuclear Force: Strong nuclear force can be defined as an attractive force found between neutrons and protons in the nucleus. It acts equally between a neutron and a neutron, a proton and a proton, and a neutron and a proton and it is charge–independent.
• Electromagnetic Force: Electromagnetic Force can be defined as the force existing between charged particles. The charges at rest have electric charges which are visible in unlike charges and repulsion which is in between like charges. Charges in motion create a magnetic force.
• Weaker Nuclear Force: Weaker nuclear force can be defined as a force that appears in only specific nuclear processes like the decay of the nucleus. At the time of decay, the nucleus will be emitting an electron and an uncharged particle known as the neutrino.

Read more on: Electromagnetic Force

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Conservation Law

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The conservation law is defined as the hypothesis based on experiments and observations which are not able to be proven but can be verified through experiments.

• Law of Conservation of Masses: 

The rearrangement of atoms in different molecules is known as a chemical reaction. The difference is formed as the reaction is exothermic while the total binding energy of the reacting molecule will be less than the total binding energy of the product molecules. As the atoms are rearranged but not destroyed the summation of the masses of the reactants will be identified as the total mass of the products. Mass will be in relation to energy, E = MC², where C is the speed of light in a vacuum.

Read about: Law of Conservation of Masses in Detail

• Law of Conservation of Energy: 

According to the general law of conservation of energy, the energies are fixed over time and will transform from one form to another. The law of conservation of energy is applied to the whole universe as it is considered that the total energy of the universe is fixed.

• Law of Conservation of Angular Momentum:

The isotropy of the space depicts that no intrinsically preferred direction in space specifies the law of conservation of angular momentum.

• Law of Conservation of Linear Momentum:

The symmetry of the law of nature along with the respect to translation in space is known as the law of conservation of linear momentum. The law of gravity on Earth is the same as the law of gravity of the Moon even though acceleration due to gravity is 1/6 of that of Earth.

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Things To Remember

• Science: Science can be defined as a systematic way to understand natural phenomena in as much detail and depth as possible and use the knowledge to modify, predict, and control the phenomena.
• Physics: It can also be defined as the study of the physical world and matter and its movement through space and time along with topics like energy, force, and many more.
• The fundamental forces in nature are gravitational force, strong nuclear force, electromagnetic force, and weaker nuclear force.
• Law of conservation: Law of conservation of masses, the law of conservation of energy, the law of conservation of angular momentum, and the law of conservation of linear momentum.

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Previous Year Questions

1. If the unit of force and length are doubled, the unit of energy will be… [KEAM]
2. The resistance R=V/I where V=... [KEAM]
3. An experiment measures quantities a, b and c, and quantity… [KEAM]
4. In order to measure the period of a single pendulum using a stop clock… [KEAM]
5. The following figure gives the movement of an object… [KEAM]
6. A force F is applied on a square plate of side L… [KEAM]
7. The magnetic induction field has the dimensions of… [KEAM]
8. Dimensional formula of Stefan's constant is… []KEAM
9. lf the length of a seconds pendulum is increased by… [KEAM]
10. A Force F is given by…
11. The length, breadth and thickness of a block are given by…
12. In an experiment, on the measurement of g using a simple pendulum…
13. From the following combinations of physical constants… [JEE MAIN 2014]
14. Dimensional formula for thermal conductivity is… [JEE MAIN 2020]
15. A quantity x is given by… [JEE MAIN 2020]
16. Amount of solar energy received on the earth's surface per unit area per unit… [JEE MAIN 2020]
17. A screw gauge has 50 divisions on its circular scale… [JEE MAIN 2020]
18. The density of a material in SI units is… [JEE MAIN 2019]
19. n terms of resistance R and time T… [JEE MAIN 2014]
20. A, B, C, and D are four different physical quantities having different dimensions… [JEE MAIN 2016]