The Act of Friction: Definition and Measurement

Friction is the force that results in the prevented motion of an object. Friction is everywhere, when one object comes into contact with another there is friction. The force acts in the opposite direction to the was the object is being pushed , pulled or twisted . When a car is at a stop sign, the car has stopped because of the friction between the brakes and the wheels. If you run down the sidewalk and want to stop quickly, you can because of the friction between your shoes and the cement allows this to. What happens if you run down the sidewalk and you try to stop on a wet surface?

Friction is still there, but the liquid makes the surfaces smoother and the friction a lot less. Less friction means it is harder to stop. Low friction happens to vehicles on a rainy/wet day. That's why there are often so many accidents. The brakes still have friction but it is limited, both the wheels and the brakes may be wet preventing the normal braking process to occur. Cars hydroplane/ drift when they go too fast on puddles of water. Friction can only happen with solid objects, but in liquids and gases there is still resistance just not friction This doesn't involve sliding surfaces like friction does, but is instead the kind of resistance you get if you try to push your way through a crowd.

This is because two surfaces/ objects ha. If the gas is air, this is referred to as air resistance. If you were in the space shuttle and re-entering the atmosphere, the bottom of the shuttle would be getting very hot. The collisions that occur between the molecules of the air being compressed by the shuttle, heat up the air and the shuttle itself. The temperature on the top of the shuttle is also warm, but nowhere near the temperatures found on the bottom. Although liquids offer resistance to objects moving through them, they also smooth surfaces and reduce friction. Liquids tend to get thinner (less viscous) as they are heated. It’s alike the viscosity of the oil you put in your car. Car engines have a lot of moving parts, and they rub on each other. The rubbing produces friction and the result is heat. When oil is added to a car engine, the oil sticks to surfaces, and helps to decrease the amount of friction and wear on the parts of the engine. An engine that runs hotter requires a more viscous oil in order for it to stick to the surfaces properly.

Measures of friction are based on the type of materials that are in contact. Concrete on concrete has a very high coefficient of friction. That coefficient is a measure of how easily one object moves in relationship to another. When you have a high coefficient of friction, you have a lot of friction between the materials. Concrete on concrete has a very high coefficient, and Teflon on most things has a very low coefficient. Teflon is used on surfaces where we don't want things to stick; such as pots and pans. Scientists have discovered that there is even lessfriction in your joints than in Teflon! It is one more example at how efficient living organisms can be.