This is called viscosity — the more viscosity, the thicker the liquid. For example, honey is more viscous than water ; oil is more viscous than milk. If you are running and want to stop, the friction between the soles of your shoes and the pavement allows you to stop. But if you try to stop as you hit a puddle, you will slide because the water on the pavement lessens the friction by making the two surfaces smoother. This is the effect of friction being reduced by water or any liquid on the road.
The use of logs and the invention of the wheel was one of the ways man tried to reduce friction and make an object move more smoothly. Friction can also generate heat. If you rub your hand back and forth quickly on the carpet, you will feel the heat caused by friction. If you constantly use the brakes of a car, eventually the brakes will fail because the material on the brake drums has been worn away resulting in metal touching metal.
For example, you would have to push a book harder to get it moving on a carpet than you would on a wooden floor. This is because there is more friction between the carpet and the book than there is between the wood and the book.
One kind of friction or resistance is air resistance. Air resistance occurs between the surface of a falling object and the air that surrounds it and it also works to slow the rate at which the object falls.
Air resistance works with surface area, so the more surface area, the more air resistance. Think about when you drop two pieces of paper: one crumpled and one flat. The crumpled one falls faster because there is less air resistance acting on the paper. Friction can be useful. For example, friction between our shoes and the floor stop us from slipping and friction between tyres and the road stop cars from skidding. Friction is sometimes unhelpful. For example, if you don't lubricate your bike regularly with oil, the friction in the chain and axles increases.
Your bike will be noisy and difficult to pedal. When there is a lot of friction between moving parts, energy is lost to the surroundings as heat. Think of what happens when you rub your hands together quickly. The friction warms them up. When one object is sliding on another it starts to slow down due to friction.
This means it loses energy. However, the energy doesn't disappear. It changes from moving energy also call kinetic energy to heat energy. By rubbing them we generate friction and, therefore, heat.
Friction is the resistance of motion when one object rubs against another. Anytime two objects rub against each other, they cause friction. Friction is also a great help to us.
After all, we would all just be sliding around everywhere if there wasn't friction to keep us steady! Friction is also used in car brakes, when we walk or climb a hill, in sandpaper, making a fire, and more. Friction has many uses in life. You light a match using friction. As you strike a match, friction creates enough heat to ignite a chemical compound in the match head that then burns the rest of the match head.
Car brakes work because of friction. Shoes designed for some sports have special soles to use friction to your advantage. Football boots have studs to increase friction by sticking to cracks in the ground.
A violinist puts rosin on his bow to increase friction between the bow and the violin strings, therefore producing sound. However, friction can also be a real nuisance. If a door hinge squeaks, the noise is caused by friction. Cooked foods tend to stick to pans. Teflon on non-stick cookware reduces friction between the food and the pan, causing the food to slide.
Competitive swimmers wear specially designed racing suits to reduce the friction between themselves and the water so that they can swim faster. Friction with the air exerts a force on anything that tries to move through it. This is called air resistance. Moving through water can be hard work, since friction with the water slows things down. This force is called water resistance.
An iron weight will slide much more easily down a slope if it has oil spread underneath it. Adding a layer of oil between two surfaces makes them slippery and reduces friction. This is called lubrication. Oil and grease are often used in machines to reduce friction between moving parts and stop the metal from wearing away.
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