Advantages and Disadvantages of Friction Our paper: Three Brothers of Friction Three brothers refer to static friction, sliding friction and rolling friction, all of which are members of the friction family. Speaking of friction, everyone must be familiar with it, because friction is a common phenomenon in our lives, and we are dealing with it all the time. We walk, eat and wash clothes by friction. The operation of all kinds of vehicles depends on friction, and the operation of machines is also inseparable from friction; Even building a house is inseparable from friction. In modern cars, 20% of the power is used to overcome friction; The friction loss of piston engine in aircraft accounts for 10% of power, and even the most advanced turbojet engine needs to overcome the friction loss of 2%. There are thousands of cars and planes in the world, so it's a pity how much fuel is wasted every year. But more seriously, friction will also cause the wear and tear of machine parts. It is reported that the loss of Britain in this respect exceeds $2 billion every year. Friction not only leads to wear, but also leads to overheating of aviation and spacecraft, which is another difficult problem encountered by modern science and technology. When the plane lands, the gate valve and the brake wheel will rub to produce red heat, which will make the brake material soft and deteriorate. Expensive brake shoes and wheels are usually scrapped after only a few uses. When the spacecraft returns to the ground, the whole ship will turn into a red fireball due to the friction between the hull flying at high speed and the air. In order to protect the astronauts and all kinds of instruments and equipment in the spacecraft, people have to pay a high price, make the hull with special alloy with high temperature resistance, and install high temperature resistant materials outside. In order to control friction and make the three brothers of friction better serve mankind, people have been carrying out arduous research and exploration. As early as15th century, Leonardo da Vinci began to study friction. In the 17 and 18 centuries, there was an upsurge of friction research in France, and Coulomb completed the concave-convex theory of friction according to Leonardo da Vinci's ideas. /kloc-in the first half of the 0/8th century, someone founded the molecular theory. After entering the 20th century, the adhesion theory reappeared. It can be said that the debate about the cause of friction continues. Concave-convex theory, molecular theory and adhesion theory are all well-founded. How to satisfactorily explain the causes of friction has always been a very active research topic. Friction and life friction are a common phenomenon. You can't push the box with little force, because there is friction between the box and the ground, which is in balance with your thrust. You pushed harder and harder, and the box was finally pushed. At this time, the thrust you use has exceeded the friction, and the box can be pushed. You keep pushing the box at a constant speed, and you have to push harder. At this time, the force you use is used to balance friction. It can be seen that the two are related. When they have happened or have happened relative motion, they will produce a force on the contact surface to hinder relative motion. This force is called friction. In fact, in daily life, although friction is a force to prevent objects from pushing each other, it is not all harmful. Sometimes it is beneficial, sometimes it is harmful. Therefore, it is necessary to increase beneficial friction and reduce harmful friction. People should use the friction between the sole and the ground when walking, which is beneficial. In order to increase friction, the sole has uneven patterns to make the contact surface rough. In order to make the braked car stop quickly, it is necessary to use the friction between the tire and the ground. On snowy days, the road surface is slippery and the friction is small, so it is not easy to stop when braking, which leads to traffic accidents. In order to reduce the occurrence of such accidents, people made uneven patterns on the tires, and sprinkled ash on the road surface when it snowed to increase friction. Prevent the car from slipping. These are all beneficial frictions to help people, so we should make rational use of them and find ways to increase them. Another example is that when a machine is working, some parts have to rotate and some parts have to rotate, so friction will be generated. This kind of friction not only makes the machine heat up, consumes labor in vain, but also wears the machine and reduces its performance. In these cases, friction is harmful and brings inconvenience to our lives. We should try our best to reduce this friction. We can increase the beneficial friction by increasing the pressure and roughening the contact surface. In order to reduce the harmful friction, we can reduce the pressure and make the contact surface smooth. Another way to reduce friction is to separate two touching objects. For example, we can add some lubricating oil to the machine, because it can form an oil film on the friction surface, so that the friction surfaces are not in contact and the moving parts only slide on the oil film. Huang Xingxiu concluded that friction is the most common force in production and life. How to use friction to benefit mankind and reduce the adverse effects brought by friction is a worldwide scientific and technological topic. By investigating the causes of friction, studying the law of its size and direction, analyzing its application in production and life, and analyzing the application of increasing friction and reducing friction in science and technology, this topic can further deepen the understanding of friction, improve the ability to collect and sort out information, and deepen the understanding of the promotion of science and technology to production and life.