{"id":24009,"date":"2022-01-25T11:34:44","date_gmt":"2022-01-25T06:04:44","guid":{"rendered":"https:\/\/infinitylearn.com\/surge\/?p=24009"},"modified":"2025-05-28T16:38:11","modified_gmt":"2025-05-28T11:08:11","slug":"cbse-class-9-science-notes-chapter-9-force-and-laws-of-motion","status":"publish","type":"post","link":"https:\/\/infinitylearn.com\/surge\/study-material\/notes\/force-and-laws-of-motion-class-9-notes-science-chapter-9\/","title":{"rendered":"Force and Laws of Motion Class 9 Notes Science Chapter 9"},"content":{"rendered":"<p><strong>Force and Laws of Motion Class 9 Notes<\/strong> \u2013 Here We have provided summary and revision notes for Class 9 Science Chapter 9. This CBSE notes contains CBSE Key Notes, CBSE Revision Notes, Short Key Notes, images, diagrams of the complete Chapter 9 titled Force and Laws of Motion of Science taught in class 9. If you are a student of class 9 who is using NCERT Textbook to study Science, then you must come across Chapter 9 Force and Laws of Motion. After you have studied lesson, you must be looking for notes to memorize. Here you can get complete Chapter 9 Force and Laws of Motion class 9 notes in one place.<\/p>\n<p>&nbsp;<\/p>\n<h2>CBSE Class 9 Science Notes Chapter 9 Force and Laws of Motion<\/h2>\n<p><strong>Facts that Matter<\/strong><\/p>\n<p><strong>Force:<\/strong> 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.<\/p>\n<p>A force can do three things on a body.<\/p>\n<ul>\n<li>It can change the speed of the body.<\/li>\n<li>It can change the direction of motion of a body.<\/li>\n<li>It can change the shape of a body.<\/li>\n<\/ul>\n<p><strong>Balanced forces:<\/strong> Forces are said to be balanced forces if they nullify one another and their resultant force is zero.<\/p>\n<p><strong>Frictional force:<\/strong> The force that always opposes the motion of objects is called a force of friction.<\/p>\n<p><strong>The second law of motion:<\/strong> The rate of change of momentum of an object is proportional to the applied unbalanced force in the direction of the force. Mathematically,<\/p>\n<p><strong>Momentum:<\/strong> 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.<\/p>\n<p><strong>1 Newton:<\/strong> A force of one Newton produces an acceleration of 1 m\/s<sup>2<\/sup> on an object of mass 1 kg.<br \/>\nIN. = 1 kg m\/s<sup>2<\/sup> (F = ma)<\/p>\n<p><strong>Third law of motion:<\/strong> To every action, there is an equal and opposite reaction and they act on two different bodies.<\/p>\n<p><strong>Conservation of momentum:<\/strong> 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.<\/p>\n<p>Suppose A and B are two balls, they have mass m<sub>A<\/sub> and and initial velocities u<sub>A<\/sub> and u<sub>B<\/sub> 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.<\/p>\n<p><strong>Unbalanced forces:<\/strong> 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.<\/p>\n<p><strong>First law of motion:<\/strong> An object remains in a state of rest or of uniform motion in a straight line unless acted upon by an external unbalanced force.<\/p>\n<p><strong>Inertia:<\/strong> The natural tendency of an object to resist a change in their state of rest or of uniform motion is called inertia.<br \/>\nThe mass of an object is a measure of its inertia.<br \/>\nIts S.I. unit is kg.<br \/>\nA body with greater mass has greater inertia.<br \/>\n(m<sub>A<\/sub>u<sub>A<\/sub> + m<sub>A<\/sub>u<sub>B<\/sub>) is the total momentum of the two balls A and B before collision and (m<sub>A<\/sub>v<sub>A<\/sub> + m<sub>B<\/sub>v<sub>B<\/sub>) is their total momentum after the collision.<br \/>\nThe 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.<br \/>\nThis is known as the law of conservation of momentum.<\/p>\n<div class=\"featured-snippet\"><\/div>\n<p>&nbsp;<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Force and Laws of Motion Class 9 Notes \u2013 Here We have provided summary and revision notes for Class 9 [&hellip;]<\/p>\n","protected":false},"author":7,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_yoast_wpseo_focuskw":"Physics class 9","_yoast_wpseo_title":"","_yoast_wpseo_metadesc":"Get CBSE Science Notes for Class 9 Chapter 9 Force and Laws of Motion on Infinity learn.","custom_permalink":"study-material\/notes\/force-and-laws-of-motion-class-9-notes-science-chapter-9\/"},"categories":[92,21],"tags":[],"table_tags":[],"acf":[],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v17.9 - 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