Chapter-12-frction
- 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