eVidyarthi

Main Menu
  • eVidyarthi
  • School
    • Class 6th
      • Maths Class 6
      • Science Class 6
      • Hindi Class 6
      • Vyakaran
      • English Class 6
      • English Grammar
      • Sanskrit Class 6
      • Geography Class 6
      • Civics Class 6
      • History Class 6
    • Class 7th
      • Maths Class 7
      • Science Class 7
      • Hindi Class 7
      • Vyakaran
      • English Class 7
      • English Grammar
      • Sanskrit Class 7
      • Geography Class 7
      • Civics Class 7
      • History Class 7
    • Class 8th
      • Maths Class 8
      • Science Class 8
      • Hindi Class 8
      • Vyakaran
      • English Class 8
      • English Grammar
      • Sanskrit Class 8
      • Geography Class 8
      • Civics Class 8
      • History Class 8
    • Class 9th
      • Maths Class 9
      • Science Class 9
      • Hindi Class 9
      • व्याकरण
      • English Class 9
      • English Grammar
      • Economics Class 9
      • Geography Class 9
      • Civics Class 9
      • History Class 9
      • Sanskrit Class 9
    • Class 10th
      • Maths Class 10
      • Science Class 10
      • Hindi Class 10
      • Vyakaran
      • English Class 10
      • English Grammar
      • Economics Class 10
      • Geography Class 10
      • Civics Class 10
      • History Class 10
      • Sanskrit Class 10
    • Class 11
      • Maths Class 11
      • English Class 11
      • Hindi Class 11
      • Accounts Class 11
      • Physics Class 11
      • Chemistry Class 11
      • Biology Class 11
      • Economics Class 11
      • Geography Class 11
      • History Class 11
      • Political Science Class 11
      • Sociology Class 11
    • Class 12
      • Maths Class 12
      • English Class 12
      • Hindi Class 12
      • Accounts Class 12
      • Physics Class 12
      • Chemistry Class 12
      • Biology Class 12
      • Economics Class 12
      • Geography Class 12
      • History Class 12
      • Political Science Class 12
      • Sociology Class 12
    • Close
  • School – हिन्दी माध्यम
    • Class 6
      • Hindi Class 6
      • English Grammar
      • Vyakaran
      • Ganit Class 6
      • Vigyan Class 6
      • Samajik Vigyan Class 6
      • English Class 6
      • संस्कृत Class 6
    • Class 7
      • Hindi Class 7
      • English Grammar
      • Vyakaran
      • गणित Class 7
      • विज्ञान Class 7
      • सामाजिक विज्ञान Class 7
      • English Class 7
      • Sanskrit Class 7
    • Class 8
      • Hindi Class 8
      • English Grammar
      • Vyakaran
      • गणित Class 8
      • विज्ञान Class 8
      • सामाजिक विज्ञान Class 8
      • English Class 8
      • Sanskrit Class 8
    • Class 9
      • Hindi Class 9
      • English Grammar
      • Vyakaran
      • गणित Class 9
      • विज्ञान Class 9
      • सामाजिक विज्ञान Class 9
      • English Class 9
      • Sanskrit Class 9
    • Class 10
      • Hindi Class 10
      • English Grammar
      • Vyakaran
      • गणित Class 10
      • विज्ञान Class 10
      • सामाजिक विज्ञान Class 10
      • English Class 10
      • Sanskrit Class 10
    • Class 11
      • गणित Class 11
      • English Class 11
      • Hindi Class 11
      • अर्थशास्त्र Class 11
      • भूगोल Class 11
      • इतिहास Class 11
      • राजनितिक विज्ञान
      • समाजशास्त्र Class 11
      • भौतिक विज्ञान Class 11
      • रसायन विज्ञान Class 11
      • जीव विज्ञान Class 11
    • Class 12
      • गणित Class 12
      • English Class 12
      • Hindi Class 12
      • अर्थशास्त्र Class 12
      • भूगोल Class 12
      • इतिहास Class 12
      • राजनितिक विज्ञान
      • समाजशास्त्र Class 12
      • भौतिक-विज्ञान Class 12
      • रसायन विज्ञान Class 12
      • जीव विज्ञान Class 12
    • Close
  • बिहार बोर्ड
    • Class 6
      • हिंदी Class 6
      • Vyakaran
      • English Grammar
      • गणित Class 6
      • विज्ञान Class 6
      • English Class 6
      • सामाजिक विज्ञान Class 6
      • Sanskrit Class 6
    • Class 7
      • हिंदी Class 7
      • Vyakaran
      • English Grammar
      • गणित Class 7
      • विज्ञान Class 7
      • English Class 7
      • सामाजिक विज्ञान Class 7
      • Sanskrit Class 7
    • Class 8
      • हिंदी Class 8
      • Vyakaran
      • English Grammar
      • गणित Class 8
      • विज्ञान Class 8
      • English Class 8
      • सामाजिक विज्ञान Class 8
      • Sanskrit Class 8
    • Class 9
      • हिंदी Class 9
      • Vyakaran
      • English Grammar
      • गणित Class 9
      • विज्ञान Class 9
      • English Class 9
      • सामाजिक विज्ञान Class 9
      • Sanskrit Class 9
    • Class 10
      • हिंदी Class 10
      • Vyakaran
      • English Grammar
      • गणित Class 10
      • विज्ञान Class 10
      • English Class 10
      • सामाजिक विज्ञान Class 10
      • Sanskrit Class 10
    • Close
  • एमपी बोर्ड
    • Class 6
      • हिंदी Class 6
      • Vyakaran
      • English Grammar
      • English Class 6
      • संस्कृत Class 6
      • गणित Class 6
      • विज्ञान Class 6
      • सामाजिक विज्ञान Class 6
    • Class 7
      • हिंदी Class 7
      • Vyakaran
      • English Grammar
      • English Class 7
      • संस्कृत Class 7
      • गणित Class 7
      • विज्ञान Class 7
      • सामाजिक विज्ञान Class 7
    • Class 8
      • हिंदी Class 8
      • Vyakaran
      • English Grammar
      • English Class 8
      • संस्कृत Class 8
      • गणित Class 8
      • विज्ञान Class 8
      • सामाजिक विज्ञान Class 8
    • Class 9
      • हिंदी Class 9
      • Vyakaran
      • English Grammar
      • English Class 9
      • गणित Class 9
      • संस्कृत Class 9
      • विज्ञान Class 9
      • सामाजिक विज्ञान Class 9
    • Class 10
      • हिंदी Class 10
      • Vyakaran
      • English Grammar
      • English Class 10
      • गणित Class 10
      • संस्कृत Class 10
      • विज्ञान Class 10
      • सामाजिक विज्ञान Class 10
    • Close
  • English
    • Basic English Grammar
    • Basic English Speaking
    • English Vocabulary
    • English Idioms & Phrases
    • Personality Enhancement
    • Interview Skills
    • Close
  • Softwares
    • Microsoft Word
    • PhotoShop
    • Excel
    • Illustrator
    • PowerPoint
    • Close
Class 9th Science || Menu
  • MCQ Science Class 9
  • Notes Science Class 9
  • Sample Papers Science Class 9
  • Solutions Science Class 9
  • Book Science Class 9
  • Syllabus Science Class 9
  • Matter in Our Surroundings
  • Is Matter Around Us Pure
  • Atoms and Molecules
  • Structure of Atom
  • Fundamental Unit of Life
  • Tissues
  • Motion
  • Force and Laws of Motion
  • Gravitation
  • Work and Energy
Share on WhatsApp

Notes Class 9 Science Chapter 9 Force and Laws of Motion

Ads

Notes For All Chapters Science Class 9

Facts that Matter

Force: It is a push or pulls on an object that produces an acceleration in the body on which it acts. S.I. unit of force is Newton.

A force can do three things on a body.

  • It can change the speed of the body.
  • It can change the direction of motion of a body.
  • It can change the shape of a body.

Balanced forces: Forces are said to be balanced forces if they nullify one another and their resultant force is zero.
force-laws-motion-cbse-notes-class-9-science-1

Frictional force: The force that always opposes the motion of objects is called a force of friction.

The second law of motion: The rate of change of momentum of an object is proportional to the applied unbalanced force in the direction of the force. Mathematically,
force-laws-motion-cbse-notes-class-9-science-2

Momentum: The momentum of an object is the product of its mass and velocity and has the same direction as that of the velocity. Its S.I. unit is kg m/s.
force-laws-motion-cbse-notes-class-9-science-3
1 Newton: A force of one Newton produces an acceleration of 1 m/s2 on an object of mass 1 kg.
IN. = 1 kg m/s2 (F = ma)

Third law of motion: To every action, there is an equal and opposite reaction and they act on two different bodies.

Conservation of momentum: If the external force on a system is zero, the momentum of the system remains constant i.e., in an isolated system, the total momentum remains conserved.
force-laws-motion-cbse-notes-class-9-science-4
Suppose A and B are two balls, they have mass mA and and initial velocities uA and uB as shown in above figure before collision. The two bodies collide and force is exerted by each body. There is change in their velocities due to collision.

Unbalanced forces: When two opposite forces acting on a body, move a body in the direction of the greater force or forces which brings motion in a body are called as unbalanced forces.

First law of motion: An object remains in a state of rest or of uniform motion in a straight line unless acted upon by an external unbalanced force.

Inertia: The natural tendency of an object to resist a change in their state of rest or of uniform motion is called inertia.
The mass of an object is a measure of its inertia.
Its S.I. unit is kg.
A body with greater mass has greater inertia.
(mAuA + mAuB) is the total momentum of the two balls A and B before collision and (mAvA + mBvB) is their total momentum after the collision.
The sum of momenta of the two objects before collision is equal to the sum of momentum after the collision, provided there is no external unbalanced force acting on them.
This is known as the law of conservation of momentum.

Ads

Android App

eVidyarthi

Evidyarthi on Facebook

Like us on Facebook

YouTube Channels

Social Science Class 6
Social Science Class 8
Learn English
English Through हिन्दी
Job Interview Skills
English Grammar
हिंदी व्याकरण - Vyakaran
Mathematics Class 6th
Social Science Class 6
Science Class 6th
हिन्दी Class 6th
Mathematics Class 7th
Science Class 7th
हिन्दी Class 7th
Mathematics Class 8th
Social Science Class 8
Social Science Class 8
Science Class 8th
हिन्दी Class 8th
Mathematics Class 9th
English Class 9th
Science Class 9th
Mathematics Class 10th
English Class 10th
Mathematics Class XI
Chemistry Class XI
Accountancy Class 11th
Accountancy Class 12th
Mathematics Class 12th
Microsoft Word
Microsoft Excel
Microsoft PowerPoint
Adobe PhotoShop
Adobe Illustrator
Learn German
Learn French
IIT JEE
Privacy Policies, Contact Us
Copyright © 2022 eVidyarthi and its licensors. All Rights Reserved.