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1. Newton’s law of Universal Gravitation

In spite of some hard work done earlier by Gilbert, Bouillard and Alfonso Borelli, the credit for discovering the law of gravitation rightly goes to Sir Isaac Newton (1687). What is the statement of the law? What is the vector notation for the gravitational force? What is the value of gravitational constant and who determined it? How to find the gravitational force between two extended bodies? What is gravity?The video lecture “Law of Gravitation” answers some of these questions, and more.

2. Problems on Newton’s Law of Gravitation

3. Determination of Gravitational Constant G

4. Gravity

5. Variation of Acceleration Due to Gravity I

6. Variation of Acceleration Due to Gravity II

7. Problems on Variation of Acceleration Due to Gravity

8. Kepler’s Laws of Planetary Motion

The three laws of planetary motion were published by Johannes Kepler between 1609 and 1619. The laws inspired Newton to think ‘why do the planets move?’ and to discover eventually the law of gravitation! What do the laws actually say? How elongated are the planetary orbits? From which principle does the law of equal areas follow? How does the period of revolution of a planet vary with orbital radius? The video lecture “Kepler's Laws” answers some of these questions, and more.

9. Gravitational Field

10. Gravitational Potential Energy

11. Gravitational Potential

12. Gravitational Field and Potential Due to Extended Bodies I

According to Newton's theory of gravitation, two bodies can exert gravitational force on each other without being in physical contact. Early scientists including Newton were not comfortable with this action-at-a-distance concept. It was Michael Faraday who settled the matter amicably by proposing ‘field theory’ in 19th century. What is gravitational field? What is gravitational potential? Are these quantities scalars or vectors? How to find gravitational field if the potential is known? The video lecture “Gravitational Field and Potential” answers some of these questions, and more.

13. Gravitational Field and Potential Due to Extended Bodies II

14. Problems on Gravitational Field and Potential Due to Extended Bodies

15. Escape Speed

If a body is thrown from the ground with a certain minimum speed, it will escape to outer space without ever coming back. What is this minimum speed? Does it depend on the mass of the body or the direction of throw? What if the body is thrown from the top of a mountain or the bottom of a crater? How is escape speed related to orbital speed of a satellite skimming around the earth? The video lecture “Escape Speed and Orbital Speed” answers some of these questions, and more.

16. Problems on Escape Speed

17. More Problems on Escape Speed and Gravitational Potential

18. Natural and Artificial Satellites of Planets

19. Problems on Orbital Motion of Satellites

20. Mechanical Energy of Satellite-Earth System

21. More Problems on Mechanical Energy of Satellite-Earth System