1. What Is Friction?
Friction is a contact force that opposes motion between two surfaces that are touching. It acts in the opposite direction of movement.
Whenever you walk, write, slide an object, or even try to push something, friction plays an important role.
1.1. Why Friction Occurs
Even smooth surfaces have tiny irregularities. When two surfaces touch, these irregularities interlock and resist motion, creating friction.
1.2. Friction Depends on Surfaces
Rough surfaces produce more friction. Smooth surfaces produce less friction.
2. Types of Situations Where Friction Acts
Friction acts whenever there is motion or an attempt to move objects.
2.1. When Objects Slide
You experience friction when you slide a box on the floor. The floor resists the motion.
2.2. When Objects Try to Move
Even if the object does not move, friction acts. For example, when you try to push a heavy sofa but it does not move, friction balances your push.
2.3. When Objects Roll
Rolling objects like wheels experience rolling friction, which is smaller than sliding friction.
3. Friction Can Be Useful
Without friction, daily activities would be extremely difficult or impossible.
3.1. Examples of Useful Friction
- Walking is possible because friction prevents your foot from slipping.
- Writing with a pen or pencil works due to friction between the tip and paper.
- Brakes in vehicles use friction to stop wheels.
- Nails and screws stay in place because of friction with wood.
4. Friction Can Also Be Undesirable
Although friction helps us in many ways, it can also cause problems.
4.1. Examples of Harmful Effects
- Friction causes wear and tear of machine parts.
- It wastes energy by producing heat.
- More fuel is needed in vehicles because of friction in engines and tyres.
5. Factors Affecting Friction
Many factors determine the amount of friction between surfaces:
5.1. Nature of Surfaces
Rougher surfaces have more friction. Smoother surfaces have less friction.
5.2. Force Pressing the Surfaces Together
The heavier an object is, the more friction it experiences because it presses the surfaces together more strongly.
5.3. Presence of Lubricants
Oils, grease, and other lubricants reduce friction by making surfaces smoother.
6. Examples of Friction in Daily Life
Friction is present everywhere in our surroundings.
6.1. Common Examples
- Shaking hands generates a little heat due to friction.
- Tyres grip the road because of friction.
- A matchstick lights because friction produces heat.
- Sandpaper rubs off material due to high friction.