- Rubber on concrete: The rough texture of concrete and the high coefficient of friction of rubber create a lot of friction between these two surfaces. This is why tires create friction with the road, allowing vehicles to move and stop.
- Metal on metal: Metal surfaces, especially those that are rough or jagged, can create a lot of friction. This is why metal bearings are often used to reduce friction between moving parts in machines.
- Sandpaper: Sandpaper is made of abrasive particles that create a lot of friction when they come into contact with other surfaces. This is why sandpaper is used for sanding down rough surfaces or removing paint.
- Dry skin on dry skin: Dry skin can create a lot of friction, especially when it is rubbed together. This can cause irritation, redness, and pain.
On the other hand, surfaces that create less friction include:
- Ice on ice: Ice is a very smooth surface, and the water molecules on its surface form a thin layer of liquid water that reduces friction. This is why ice rinks are so slippery.
- Teflon on Teflon: Teflon is a very smooth and slippery material, and it creates very little friction when it comes into contact with itself. This is why Teflon is used in non-stick cookware and other applications where low friction is desired.
- Air on air: Air is a very thin gas that creates very little friction. This is why airplanes can fly through the air with relatively little resistance.