Gravitation Class 9 Notes

Greetings to all, Today we are going to upload the Gravitation Class 9 Notes PDF to assist students. Class 9 Science introduces you to the most fascinating chapters and concepts you have been studying for the past few years. In Class 9 Science, you will delve a little deeper and get to know more about various natural phenomena and learn how they happen. Class 9 Science Chapter 10 is on gravitation and the things happening around us related to it. To understand the chapter better, you can refer to the Gravitation Class 9 notes prepared by the highly experienced.
You will be able to understand the concepts related to gravitation, the law of Gravitation Chapter 10 from these revision notes and prepare the chapter well. Every section of these notes has been compiled in such a way that students can understand the new concepts, learn the formulas, and can solve various questions easily with the help of these notes.

Gravitation Class 9 Notes PDF – Short Notes

Toss a stone from a great height. What are your observations? 

• The stone, which was at first at rest, begins to move towards the ground and reaches its maximum speed right before it meets it.
• The stone is not traveling at a constant rate. Its speed fluctuates at all times, indicating that the stone is accelerating.
• A force is necessary to cause an acceleration in a body, according to Newton’s second law of motion.
• The stone was not pushed or pulled in any way. What was the source of the force?
• Sir Isaac Newton came up with the solution to this dilemma after seeing an apple fall from a tree.
• The apple, on the other hand, is unable to draw the Earth since the force it exerts on it is insignificant.

The Universal Law of Gravitation or Newton’s Law of Gravitation:

• The universal law of gravitation is a mathematical relationship that Sir Isaac Newton proposed to measure the gravitational force.
• According to this law “Every particle in the universe attracts every other particle with a force which is directly proportional to the product of their masses and inversely proportional to the square of the distance between them, the direction of the force being along the line joining the masses”.
• Consider two mass

m1m1
and
m2m2
objects separated by a distance
dd
. The gravitational force
FF
is proportional to the product of the masses, according to Newton’s law.
F ∝ m1m2 …… (1)F ∝ m1m2 …… (1)
and inversely proportional to the square of the distance between the masses
F ∝ 1d2 …… (2)F ∝ 1d2 …… (2)
Two Objects of Masses
m1m1
and
m2m2
separated by a distance
dd
Inversely proportional is always represented as directly proportional to the reciprocal of that quantity.
Combining equation
(1)(1)
and equation
(2)(2) we get
F ∝ m1m2d2F ∝ m1m2d2
F ∝ Gm1m2d2 ……. (3)F ∝ Gm1m2d2 ……. (3)
Where GG is a proportionality constant known as the universal gravitational constant.
GG is known as the universal constant because its value remains constant throughout the cosmos and is unaffected by object masses.
Universal Gravitational Constant:

• The mathematical form of Newton’s Law of Gravitation is

F = Gm1m2d2F = Gm1m2d2
If m1 = m2=1m1 = m2=1  and d = 1d = 1 then
F = G × 1 × 112F = G × 1 × 112
F = GF = G

• As a result, the universal gravitational constant can be defined as the gravitational force that exists between two unit masses separated by a unit distance.
• SISI

Separated by a Distance
dd
 When the masses of both bodies are doubled, the force of attraction is given as;
F3 = G2m2md2F3 = G2m2md2
F3 = 4Gm2d2F3 = 4Gm2d2
F3 = 4F1F3 = 4F1
That is whenever the mass increases the force of attraction also increases.
Dependence of Gravitational Force on Distance:
The force of attraction between two bodies is inversely proportional to the square of their distance, according to the universal law of gravitation.
 Force of Attraction Between Two Bodies of Mass
mm
Separated by a Distance
dd
 F1 = Gm1m2d2F1 = Gm1m2d2
= Gm2d2 = Gm2d2
Here, two bodies of mass
mm
are separated by a distance
dd
and hence,
F1 = Gm2d2F1 = Gm2d2
you can Download the Gravitation Class 9 Notes PDF by clicking on the link given below