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[PDF] Download Revision Notes for Class 8 Science Chapter 12 Friction
Here we are providing revision notes for class 8 science. We have two types of revision notes for class 8 science (i) Short revision notes (ii) Detailed revision notes. In this article, we are covering short revision notes for CBSE class 8 science Chapter 12 Friction.
Friction Class 8 Revision Notes
Friction is a force that opposes the relative motion between two surfaces of objects in contact. The force of friction always acts in a direction opposite to that of the applied force.
Causes of Friction: Friction exists between two surfaces due to irregularities on the surfaces of the objects in contact, interlocking of micro-level irregularities of the two surfaces and ploughing of harder surfaces into smoother surfaces.
Factors That Affect Friction
- Roughness of the surface
- The extent to which the two surfaces press together
- Nature of the surface
Types of Friction:
(i) Static Friction: When a body is at rest, the force of friction is called the static friction and is always equal and opposite to the applied force. The force of friction which acts when the body is just at the verge of sliding on the surface is called limiting friction.
(ii) Sliding friction: The friction force which opposes the actual relative sliding motion between two contact surfaces. Sliding friction is smaller than static friction.
(iii) Rolling Friction: The frictional force that exists between two surfaces when a body rolls over the other. Rolling friction is smaller than sliding friction.
Effects of Friction
- Friction produces heat.
- Friction causes wear and tear.
- Friction opposes motion.
Advantages of Friction
- Friction between pen and paper enables us to write on the paper.
- Friction between our feet and the ground allows our movements like standing, walking and running.
- Friction between the surface of the road and tyres of our vehicles allow the vehicles to move without slipping.
Disadvantages of Friction
- Friction causes moving objects to stop or slow down.
- Friction produces heat causing wastage of energy in machines.
- Friction causes wear and tear of moving parts of machinery, soles of shoes, etc.
Friction is a necessary Evil: As friction is advantageous to us it is considered as a friend but due to its disadvantages it is a foe. Depending on the circumstance, friction can be a help or a hindrance. Thus it is a necessary evil.
Increasing Friction: By pressing the surfaces together more strongly. For e.g. when brakes are applied on a bicycle or car, the brake pads press against a moving part of the wheel and the force of friction increases.
Friction can be increased by increasing the roughness of the surfaces in contact. For example, treading of shoes and tyres is done to increase friction.
Reducing Friction: Friction between the sliding surfaces of two objects can be reduced by making the surfaces in contact smooth by polishing them.
Sliding friction between the moving parts of vehicles and machinery can be reduced by using oil, grease, graphite or any other lubricant.
Rolling friction is less than sliding friction. Hence, sliding friction is replaced by rolling friction by using rollers, like ball bearings between the hub and the axles in the moving parts of machines and vehicles.
Friction is reduced by providing wheels, e.g., suitcase, school bags of kids, etc.
Aeroplanes, boats, fishes and birds which move through fluids have bodies of special shape, called streamlined shape, so as to reduce the friction due to fluid and avoid energy loss.
Chapter List
Chapter 1 Crop Production and Management
Chapter 2 Microorganisms: Friend and Foe
Chapter 3 Synthetic Fibres and Plastics
Chapter 4 Materials: Metals and Non-Metals
Chapter 5 Coal and Petroleum
Chapter 6 Combustion and Flame
Chapter 7 Conservation of Plants and Animals
Chapter 8 Cell Structure and Functions
Chapter 9 Reproduction in Animals
Chapter 10 Reaching the Age of Adolescence
Chapter 11 Force and Pressure
Chapter 12 Friction
Chapter 13 Sound
Chapter 14 Chemical Effects of Electric Current
Chapter 15 Some Natural Phenomena
Chapter 16 Light
Chapter 17 Stars and the Solar System
Chapter 18 Pollution of Air and Water
Benefits of Using One Page Revision Notes for Class 8 Science
Here are the benefits of using one-page revision notes for CBSE Class 8 Science:
- Concise Overview: One-page revision notes condense important information from each chapter into a single page, providing a quick and comprehensive overview of the entire syllabus.
- Time-Saving: These notes save valuable study time as they allow students to quickly review key concepts without going through lengthy textbooks or extensive notes.
- Effective Recap: One-page notes serve as an efficient tool for last-minute revision before exams, helping students refresh their memory and reinforce their understanding of critical topics.
- Easy to Carry: Students can easily carry these compact notes anywhere, making them convenient for on-the-go studying, whether at school, home, or during travel.
- Improved Focus: The condensed format encourages students to concentrate on the most essential points, reducing the risk of distraction from irrelevant information.
- Enhanced Retention: Summarized information is easier to remember, making it ideal for retaining key concepts and formulas for the exam.
- Organization: One-page notes often follow a structured format, aiding in the organization of information and making it easier for students to locate specific topics.
- Quick Reference: During the exam, one-page notes can be used as a quick reference guide to quickly recall important facts and concepts.
- Boosted Confidence: Having concise revision notes can boost students’ confidence in their exam preparedness, as they can easily review the entire syllabus in a short amount of time.
- Customization: Students can create their own one-page notes, allowing them to personalize the content to suit their learning style and preferences.
- Comprehensive Coverage: Despite their brevity, one-page notes should cover all essential topics and concepts, ensuring students don’t miss any important information.
In summary, one-page revision notes for CBSE Class 8 Science offer a convenient and effective way for students to review and consolidate their knowledge, ultimately aiding in better exam performance.
