Gravitation - Notes, Topics, Formulas, Books, FAQs

Have you ever wondered how you can walk on the ground freely ? or when a fruit falls from a tree or something drops from a height, it always heads for the ground? This is exactly what Sir Isaac Newton wondered and offered the world the concept of gravitation. In simple words, Gravitation is the force operating between two objects on the earth. So any thrown object will be attracted toward the earth and will fall on earth. The gravitational force has a very important role which allows us to live in this wonderful world. If gravity disappeared suddenly then we would all start to float immediately. So it is very important to study about Gravitational. And this chapter will help you to understand various laws, various properties of gravitational force along with the application of these laws and properties.

Gravitation is one of the most important chapters from mechanics while preparing for all competitive exam. Because it helps you to understand about gravitational force, field, etc which is the basis of many theories which we study under physics. Gravitation is easy to understand and a high scoring topic. You will get at least one question from this chapter. Gravitation and Electrostatics are conceptually similar to each other so when you study Electrostatics after studying gravitation, you will understand its concepts easily. The Concept of Gravitation and other chapters of mechanics are mixed in miscellaneous questions which are asked in competitive exams.

Notes on Gravitation-

So we will discuss step by step about important topics from this chapter followed by an overview of this chapter.

Then we will understand important formulas from this chapter. Remembering these formulas will increase your speed while question-solving.

Gravitation Topics

• The universal law of gravitation.

• Acceleration due to gravity

• Kepler's laws of planetary motion.

• Gravitational potential energy; gravitational potential.

• Escape velocity. Orbital velocity of a satellite. Geostationary satellites.

Overview of Gravitation

In this chapter, you will learn about one of the fundamental force which is a gravitational force. You will also learn to calculate its magnitude with the help of formula that we get from Newton's Law of Gravitation. Now Let's try to understand the gravitational force with the help of Newton's Law of Gravitation

Newton's Law of Gravitation-

Gravitational force is an attractive force acting between two masses and separated by a distance r. This force is directly proportional to the and inversely proportional to .

After studying that Gravitation force operates between any two objects on the earth, You may wonder and ask why not all bodies attract each other and stick together due to gravitational force. So answer to this question is that Gravitational Force is the weakest among all the four fundamental forces known to us till now. Let Suppose 2 similar ball of mass 1 kg are placed 1m apart then the gravitational force acting between them is simply G which is equal to As you see this is a very negligible attractive force.

In this chapter, you will learn about various concept regarding acceleration due to gravity (g) with its definitions and suitable example.

Height, Depth, Shape of earth, Rotation of earth are the important factors which affect the value of g.

• Let's have a look at how g value changes due to the shape of the earth.

Radius of equator

Radius of pole

Equatorial radius is about 21 km longer than the polar radius.

So

In fact

Or we can say that Weight increases as the body are taken from equator to pole.

You will also learn about satellites and their motion in space. You will also learn to calculate their orbital velocity, their escape velocity, etc.

Related topics,

Formulas for Gravitation

1. Gravitational force-

2. Acceleration due to gravity (g)

3. Variation in 'g' with height

4. Variation in 'g' with depth

5. Variation in 'g' due to Rotation of earth

6. Gravitational field Intensity

Where F=Gravitational force

7. Gravitational Potential

or

8. Work done against gravity

9. Escape velocity

10. Escape energy

11. Kepler's 2nd law

12. Kepler's 3rd law

or

13. Energy of satellite

How to prepare Gravitation

• First, you should have good command over the concepts of Gravitation and you should also know how to apply them well at the time of the entrance exam or while solving questions. Please try to understand each concept from this chapter, with the help of theory, questions with solutions and video lectures on each important concept.
• For each concept practice enough problems to have a thorough understanding of the concept. Solve all the questions at home with proper concentration and try to do all calculations by yourself without seeing the solution first. Through practice, you will come to know how to approach a question

• Concepts like Newton's Law of Gravitation, Acceleration due to gravity, Gravitational potential energy, Kepler’s laws of planetary motion, Escape velocity, etc are the most important concept from this chapter with respect to various competitive exam.
• Acceleration due to gravity plays a very important role to understand other concepts and solve problems easily from this chapter.
• Understand all the laws from this chapter along with their applications. With proper study, you can solve questions from this chapter with ease.

NCERT Notes Subject Wise Link:

• NCERT notes Class 11 Maths
• NCERT notes Class 11 Physics
• NCERT notes Class 11 Chemistry
• NCERT notes Class 11 Biology

Gravitation Tips

• Make a plan to prepare for this chapter and Stick to a Timetable.

• Study the concept first and then start solving questions. Don't go through question directly without knowing the concept.

• Solve previous year question of various exam from this chapter.

• Use smart methods to solve questions.

NCERT Solutions Subject wise link:

• NCERT solutions for class 11 Physics.
• NCERT solutions for class 11 Chemistry.
• NCERT solutions for class 11 Mathematics.
• NCERT solutions for class 11 Biology.

NCERT Exemplar Solutions Subject wise link:

• NCERT exemplar solutions for class 11 Physics.
• NCERT exemplar solutions for class 11 Chemistry.
• NCERT exemplar solutions for class 11 Mathematics.
• NCERT exemplar solutions for class 11 Biology.

Books for Gravitation

For Gravitation, chapter concepts in NCERT are enough but you will have to practice lots of questions including previous year questions and you can follow other standard books available for competitive exam preparation like Concepts of Physics (H. C. Verma) and Understanding Physics by D. C. Pandey (Arihant Publications).