Class 9 Exam > Class 9 Notes > Science Class 9 > Short Notes - Gravitation
Gravitation Class 9 Notes Science Chapter 9
- Universal Law of Gravitation
Every object in the universe attracts every other object with a force which is proportional to the product of their masses and inversely proportional to the square of the distance between them.
The force is along the line joining the centres of two objects.
Gravitational Force between two uniform objects is directed along the line joining their centres.Let two objects A and B of masses M and m lie at a distance of d from each other as shown in the figure.
Let F be the force of attraction between two objects. According to the universal law of gravitation - G is called a universal constant because its value does not depend on the nature of intervening medium or temperature or any other physical variable.
S.I. unit of G = Nm2/kg2
Value of G = 6.673 × 10−11 Nm2/kg2 (Found by Henry Cavendish) - Importance of Universal Law of Gravitation
Universal law of gravitation successfully explained several phenomena like :
(i) the force that binds us to the earth.
(ii) the motion of moon around the earth.
(iii) the motion of planets around the Sun.
(iv) the tides due to the moon and the Sun. - Free fall When an object falls down towards the earth under the gravitational force alone, we say the object is in free fall.
The velocity of a freely falling body changes and is said to be accelerated.
This acceleration is called acceleration due to gravity, denoted by ‘g’. Unit is m/s2.
As F = ma (∵ a = g) ...(i)
F = mg ...(ii)
and
F = G(Mm/d2) (from Universal law of gravitation) ...(iii)
From (ii) and (iii)
∴ mg = G(Mm/d2)
∴ g= GM/d2
M = Mass of the earth
d = Distance between the object and the earth
G = Gravitational constant If the object is placed on the earth then
d = R (R = radius of the earth) ...(iv)
Earth is not a sphere, it is flattened at poles.
Hence Rp − Radius at pole and Re − Radius at equator
∴ The value of ‘g’ is more at poles = (9.9 m/s2) and less at equator = (9.8 m/s2)
Calculation of value of g
g= G(M/R2
G = 6.67 x 10-11 Nm2/kg2
M = 6 × 1024 kg (Mass of the earth)
R = 6.4 × 106 m
On substituting the given values
Motion of objects under the influence of gravity ‘g’ does not depend on the mass of the body. All objects small, big, heavy, light, hollow or solid fall at same rate. - The three equations of motion viz.
(i) v = u + at
(ii) s = ut + (1/2) at2
(iii) v2 – u2 = 2as are true for motion of objects under gravity. For free fall, value of acceleration a = g = 9.8 ms–2. - If an object is just let fall from a height then in that case u = 0 and a = g = 9.8 m/s2.
- If an object is projected vertically upward with an initial velocity u, then a = – g = – 9.8 ms–2 and the object will go to a maximum height h where its final velocity becomes zero (i.e., v = 0).
- Mass
Mass of an object is the measure of its inertia. It is the matter present in it. It remains the same everywhere in the universe. - Weight
The force of attraction of the earth on the object is known as the weight of the object. Its S.I. unit is Newton.
W = m × g
The weight of an object can change from one place to the other, from one planet to the other.
Weight of an object on moon is given by the formula
Wm = weight of an object on moon
Mm = Mass of the moon = 7.36 x 1022
Rm = radius of the moon = 1.74 x 106
G = 6.67 x 10-11 Nm2/kg2
Wm = 1.474 × 1010 G × m
and We = 1.474 × 1011 G × m
∴
∴ Weight of an object on moon = (1/6) th the weight of an object on the earth. - Thrust
It is the net force applied in a particular direction. Its S.I. unit is N. - Pressure
It is the force per unit area.
Pressure = thrust / area , S.I unit = N/m2 = Pascal (pa) - Pressure in fluids
All liquids and gases are fluids, as they can flow.
The pressure exerted by a fluid is transmitted in all direction. - Buoyancy
The upward force exerted by water (fluid) on the body is known as upthrust or buoyancy.
The magnitude of the buoyant force depends on the density of the fluid.A − Wooden block
B1 − Beaker with tap water
B2 − Beaker with salty water
The buoyant force exerted in B2 is more as compared to B1. It is because the density of B2 water is more.
The object may float, sink or remain half submerged and half above water, the density of the fluid and object decides this.
– If the density of object is less than the fluid, then it will float on the liquid.
– If the density of object is more than the fluid, then it will sink in the liquid.
– If the density of object is same as the density of fluid, then it will half float and half sink. - Archimedes’ Principle
When a body is immersed fully or partially in a fluid, it experiences an upward force that is equal to the weight of the fluid displaced by it. - Its applications are:
(i) Used in designing ships and submarines,
(ii) In lactometers to find purity of milk.
(iii) In hydrometer to determine density of liquid. - Relative Density
Relative density = density of substance / density of water
It has no unit.
...(iv)
A − Wooden block
The document Gravitation Class 9 Notes Science Chapter 9 is a part of the Class 9 Course Science Class 9.
All you need of Class 9 at this link: Class 9
|
87 videos|369 docs|67 tests
|
FAQs on Gravitation Class 9 Notes Science Chapter 9
| 1. What is the concept of gravitation? |  |
Ans. Gravitation is the force of attraction that exists between any two objects with mass. It is responsible for keeping objects on the Earth's surface and planets in their orbits around the Sun.
| 2. What is the importance of studying gravitation? | |
Ans. Studying gravitation is important as it helps us understand the fundamental force that governs the motion of celestial bodies in the universe. It also helps in explaining various natural phenomena like the tides, the motion of planets, and the formation of galaxies.
| 3. How does the mass of an object affect the force of gravitation? | |
Ans. The force of gravitation between two objects is directly proportional to the product of their masses. In simple terms, the more massive an object is, the stronger its gravitational pull will be.
| 4. Does the distance between two objects affect the force of gravitation? | |
Ans. Yes, the force of gravitation between two objects decreases with an increase in the distance between them. It follows an inverse square law, meaning that if the distance is doubled, the force becomes one-fourth of its original value.
| 5. How does the gravitational force affect the motion of objects? | |
Ans. The gravitational force affects the motion of objects by pulling them towards each other. It causes objects to accelerate towards each other, resulting in various motions like falling, orbiting, or revolving around a common center of mass.
About this Document
|
3.6K Views |
|
4.70/5 Rating |
|
Nov 24, 2024 Last updated |
Document Description: Short Notes - Gravitation for Class 9 2024 is part of Science Class 9 preparation.
The notes and questions for Short Notes - Gravitation have been prepared according to the Class 9 exam syllabus. Information about Short Notes - Gravitation covers topics
like and Short Notes - Gravitation Example, for Class 9 2024 Exam. Find important definitions, questions, notes, meanings, examples, exercises and tests below for Short Notes - Gravitation.
Introduction of Short Notes - Gravitation in English is available as part of our Science Class 9
for Class 9 & Short Notes - Gravitation in Hindi for Science Class 9 course.
Download more important topics related with notes, lectures and mock test series for Class 9
Exam by signing up for free. Class 9: Gravitation Class 9 Notes Science Chapter 9
Description
Full syllabus notes, lecture & questions for Gravitation Class 9 Notes Science Chapter 9 - Class 9 | Plus excerises question with solution to help you revise complete syllabus for Science Class 9 | Best notes, free PDF download
Information about Short Notes - Gravitation
In this doc you can find the meaning of Short Notes - Gravitation defined & explained in the simplest way possible. Besides explaining types of
Short Notes - Gravitation theory, EduRev gives you an ample number of questions to practice Short Notes - Gravitation tests, examples and also practice Class 9
tests
|
Explore Courses for Class 9 exam
|
|
Signup for Free!
Signup to see your scores go up within 7 days! Learn & Practice with 1000+ FREE Notes, Videos & Tests.
Related Searches
Previous Year Questions with Solutions
,Important questions
,study material
,Semester Notes
,MCQs
,Sample Paper
,Objective type Questions
,video lectures
,mock tests for examination
,Extra Questions
,practice quizzes
,Gravitation Class 9 Notes Science Chapter 9
,Viva Questions
,ppt
,shortcuts and tricks
,Free
,Exam
,past year papers
,Summary
,Gravitation Class 9 Notes Science Chapter 9
,Gravitation Class 9 Notes Science Chapter 9
;
Additional Information about Short Notes - Gravitation for Class 9 Preparation
Short Notes - Gravitation Free PDF Download
The Short Notes - Gravitation is an invaluable resource that delves deep into the core of the Class 9 exam.
These study notes are curated by experts and cover all the essential topics and concepts, making your preparation more efficient and effective.
With the help of these notes, you can grasp complex subjects quickly, revise important points easily,
and reinforce your understanding of key concepts. The study notes are presented in a concise and easy-to-understand manner,
allowing you to optimize your learning process. Whether you're looking for best-recommended books, sample papers, study material,
or toppers' notes, this PDF has got you covered. Download the Short Notes - Gravitation now and kickstart your journey towards success in the Class 9 exam.
Importance of Short Notes - Gravitation
The importance of Short Notes - Gravitation cannot be overstated, especially for Class 9 aspirants.
This document holds the key to success in the Class 9 exam.
It offers a detailed understanding of the concept, providing invaluable insights into the topic.
By knowing the concepts well in advance, students can plan their preparation effectively.
Utilize this indispensable guide for a well-rounded preparation and achieve your desired results.
Short Notes - Gravitation
Short Notes - Gravitation Notes offer in-depth insights into the specific topic to help you master it with ease.
This comprehensive document covers all aspects related to Short Notes - Gravitation.
It includes detailed information about the exam syllabus, recommended books, and study materials for a well-rounded preparation.
Practice papers and question papers enable you to assess your progress effectively.
Additionally, the paper analysis provides valuable tips for tackling the exam strategically.
Access to Toppers' notes gives you an edge in understanding complex concepts.
Whether you're a beginner or aiming for advanced proficiency, Short Notes - Gravitation Notes on EduRev are your ultimate resource for success.
Short Notes - Gravitation Class 9 Questions
The "Short Notes - Gravitation Class 9 Questions" guide is a valuable resource for all aspiring students preparing for the
Class 9 exam. It focuses on providing a wide range of practice questions to help students gauge
their understanding of the exam topics. These questions cover the entire syllabus, ensuring comprehensive preparation.
The guide includes previous years' question papers for students to familiarize themselves with the exam's format and difficulty level.
Additionally, it offers subject-specific question banks, allowing students to focus on weak areas and improve their performance.
Study Short Notes - Gravitation on the App
Students of Class 9 can study Short Notes - Gravitation alongwith tests & analysis from the EduRev app,
which will help them while preparing for their exam. Apart from the Short Notes - Gravitation,
students can also utilize the EduRev App for other study materials such as previous year question papers, syllabus, important questions, etc.
The EduRev App will make your learning easier as you can access it from anywhere you want.
The content of Short Notes - Gravitation is prepared as per the latest Class 9 syllabus.
|
© EduRev
|
Education Revolution
|
Follow Us
|
Signup to see your scores
go up within 7 days!
Access 1000+ FREE Docs, Videos and Tests
Takes less than 10 seconds to signup