- When a race-driver says he or she lost friction, it means that the speed of the vehicle exceeded the limits of friction between the rubber tires and the racetrack, causing a spin.
- Friction is a feature that every physical entity has, to varying degrees.
- With no friction between your wheels and the asphalt, it would be impossible to move your car from the parking spot.
Friction is a type of force that appears between two surfaces that move against each other. One aspect of friction we will investigate is its ability to transform kinetic energy into thermal energy, which turns friction into a desirable effect for many actions we perform as humankind.
Friction For All
Friction is divided into several different categories based on the atomic structure and physical integrity of materials that are coming in contact. If two solid surfaces rub against each other, we are dealing with dry friction. However, friction is not something that can happen only between hard materials.
There is friction between fluids, as they can also be separated by different levels of viscosity. Viscosity itself would not exist without friction, because this feature of interaction between fluids allows some of them to be ‘’thicker’’ (in a molecular sense) than others. If this is hard to imagine, just look at what happens when your regular, everyday water interacts with oil. They are visibly and almost stubbornly separated. One other important type of friction is skin friction, which occurs as a force countering the fluids moving across a body’s surface. The skin can be human, but it can also be a shell of another physical entity, like a boat or a plane.
Friction Is A Problem?
Everything that travels through or on water meets friction as a force that is acting against its movement. The same applies to anything that can fly: air, although invisible, has a specific density, making it harder for planes to fly. You have probably seen this very specific scene in a number of movies: as the rocket is launched off the ground, all it is doing from that point onward is fighting against two things - gravity and friction.
But, once the rocket finally leaves the Earth’s atmosphere, you can see how it immediately ‘’relaxes’’, for lack of a better term. In that particular moment, the moving aircraft is liberated from the pulling forces of gravity, and it enters into space, where the friction of air is much more forgiving.
The air in outer space is not so dense like it is in our atmosphere, which weakens the forces of friction massively. However, even if a rocket is far away from any kind of gravitational forces, the effects of friction never disappear completely. Now, if we leave the zero-g atmosphere, and come back to Earth again, we can understand how some actions would either be impossible or too hard to handle if friction did not exist.
Friction Is A Hero!
For example, walking on the ground would be much more difficult. If the properties of matter that interact, which is the rubber on your shoes and all the different hard terrains you walk on, were not interrupted by friction, we would probably just slide around uncontrollably. That would probably just be funny, but the situation in traffic would be scary.
If there were no friction between your wheels and the asphalt, it would be impossible to both start, and even if you could, there would be no way you could stop once you hit the brakes. Also, those asteroids you see burning in the sky when you are lying on a slightly steep grassland (and not sliding down, thank you friction!) during long summer nights would be dangerous if friction did not take care of them when they enter our atmosphere.
Remember what we said in the beginning - about kinetic energy being transformed into thermal? That is precisely what happens with asteroids that disintegrate when they enter our home, and it is a violent, yet beautiful display of the powers of friction.