1 steel needle penetrates glass (the relationship between pressure and kinetic energy) First, a complete glass is put in the air, and then the performer will try to let a tiny steel needle penetrate the glass. Some people think that the hardness of steel is much greater than that of glass, because glass can't stand beating, and it will break when it falls, while steel is extremely tough. If you hit ordinary glass with an iron bar, it is not difficult to break the glass, but don't think that you can easily break the glass with a steel needle. In fact, the hardness of glass is greater than that of steel. If you carve steel on the glass, you will find that there is no "masterpiece" of steel left on the glass. On the contrary, glass can leave traces on steel at will. This is enough to prove that iron is not harder than glass. If you want to ask why iron can easily break glass, it comes down to the texture of the glass itself. Glass is hard and brittle, and it is easily broken by strong impact, which also explains why glass is harder than iron, but it is easily broken by iron. When iron hits the glass violently, it needs to generate enough impulse to break it, which requires iron itself to have a certain quality, but only a small steel needle is used in the magic. Obviously, it is not feasible to rely solely on the quality of the steel needle itself to break through the glass. At this time, two simple knowledge are needed to solve it. The first is the problem of pressure and stress area. We all learned in junior high school that under the same pressure, the smaller the stress area of the object, the greater the effect. This is why people should make one end pressed by hand flat and large when making thumbtacks, instead of reducing its area in order to save labor costs. This magic is also true. Through the tip of the steel needle, the glass is relatively easy to pierce. But glass is much harder than walls and wood, unlike pushing thumbtacks by hand to solve problems. This leads to another knowledge-the relationship between kinetic energy and speed. The magnitude of kinetic energy is related to the mass and velocity of an object. Here, it is obvious that tiny steel needles cannot improve kinetic energy through mass. So the speed of steel needle is the key to the success of magic. The greater the speed of motion, the greater the energy generated when hitting an object. Accidents that high-speed planes are punctured by birds in the air often happen. The bird can pass through the steel plate of the plane, so you can imagine how amazing the power was at that time. Everyone knows what will happen if the earth is hit by an asteroid. 1994, scientists photographed an asteroid with a diameter of about 50 kilometers in close contact with Jupiter. There was a huge explosion on Jupiter, covering an area even larger than the whole earth. If Jupiter is not huge enough, I'm afraid there are only eight planets in the solar system today. Asteroids can produce such amazing power because they are influenced by gravity and have enough speed when they hit. Punching through the glass requires both of the above conditions. Ensuring vertical contact with the glass and reaching a certain speed depends on the performer's skill. 2 obedient fountain (charge interaction) We must first simulate a scene and then analyze its essence. A little magician asked his assistant to move a very beautiful bonsai, including a rockery, a pool and pavilions, which embellished the whole scene with vitality, and a striking spring water gushed out from the rockery. The magician picked up a glass rod from the table and said to the audience, "The fountain in this bonsai can understand me." After that, he began to command the fountain with a glass rod. However, no matter whether his glass rod pointed to the left or right, the fountain didn't respond, so that the glass rod was sprayed with water and still didn't work. Even the audience thought that the magician's baton was out of order. However, the magician is in no hurry. He wiped the water drops on the glass rod with a piece of silk, rubbed it hard a few times, then shook the glass rod on the left of the fountain a few times, only to see that the fountain tilted slightly to the right, and then shook the glass rod on the right of the fountain, and the fountain tilted slightly to the left. This is a simulated scene, so why should the fountain obey the command? First of all, pay attention to the magician's action of cleaning the glass rod. The friction between silk and glass rod will make the glass rod lose electrons and be positively charged, so will the water droplets sprayed in bonsai. According to the principle that like charges repel each other, when the glass rod is close to the spring, the fountain will deviate in the opposite direction and play the role of "command". In addition, the magician's performance was unsuccessful from the beginning, and the glass rod was sprayed with water, completely to cover up the action of wiping the glass rod with silk cloth and rubbing it hard to make it positively charged. The cotton magic (heat transfer) that can't be done at 3 o'clock only needs a coin and a piece of cotton cloth. Wrap a coin in a piece of cotton cloth and tie it tightly. At this time, you tie the lit cigarette to the cotton cloth until it goes out. You will be surprised to find that not only does the cloth not catch fire, but it can't even zoom, leaving only a smoke spot. Is cotton cloth magic? Actually, it's not. Experiments show that metal conducts heat faster than cotton. When fireworks touch cotton cloth, the heat is immediately absorbed by coins. It is impossible for cotton cloth to reach the lowest combustion temperature, that is, the ignition point. Therefore, the cloth will not burn. This is the use of heat to transfer knowledge. Heat transfer knowledge also has many applications in life, such as a wok, which is made of metal with good heat transfer. 4 magic box (gravity and center of gravity) The magic described below is called the magic box. I saw that the performer had a black box, which was closed all around and looked a little mysterious. The performer carefully placed the box on the table and gradually pushed it onto the table with his wand. A strange scene appeared. When the box was pushed to the table by the wand, it didn't fall off and looked stable. In order to convince the masses, the performer deliberately picked up the box for inspection to make sure there was nothing special on the desktop. The audience was surprised by this. Is the box really magical, or does the performer have special functions? From a scientific point of view, obviously not. In fact, there is a mystery hidden in the box. First, the box is processed. Make a sandwich at the bottom of the box and put a heavy thing at one end, which can be lead or iron. In this way, the box is endowed with magic. As we know, any object has a center of gravity, that is, the resultant point produced by the gravity of all parts of the object. A cuboid box with uniform density, the center of gravity falls in the center of the box. Once the center of gravity falls on the table, the box will fall. But after placing a lead (iron) block in one corner of the box, the situation is different: placing a heavy object will move the center of gravity to the side close to the heavy object, which will inevitably make the center of gravity of the box fall right on the table, and the box will certainly not fall. Through this magic, we know the importance of the center of gravity, which is related to the stability of the object. If the center of gravity is not carefully handled in architectural design, the building will collapse, resulting in terrible consequences. [Exploration Results] From these magics, we easily learned a lot of physical knowledge, such as magnetism, thermal conductivity of objects, the position of the center of gravity of objects, and the relationship between speed and kinetic energy ... Magic seems complicated and unpredictable, but in fact it is simple in nature. If you can't discover the knowledge contained in it and open the door to mystery, then you can't open its magical cotton yarn. But as long as you observe carefully, think seriously and put the wings of imagination in your life, you can also perform a magic of your own. There are many wonderful performances in magic, which are carefully designed by magicians and use a lot of physical knowledge. But all these knowledge are extremely subtle truths in life, such as steel needles penetrating glass and obedient fountains. We need to learn in life and explore in experiments in order to learn more knowledge and understand more truths. In the process of collecting information, Qi Xin worked together and found many magic tricks that had never been seen before. In the process of discussion, we not only enhanced our analytical ability, but also deeply realized the magic. The miracle of the world and the wide application of physical knowledge. The magic that seemed unfathomable before was solved after everyone's thinking, and we also gained more magic knowledge than others. Through this exploration, we learned to find and solve problems in life. At the same time, we also learned a lot of physical knowledge and its practical application, which broadened our horizons. We also learned how to collect data, organize data and draw conclusions in our study. We have benefited a lot from hands-on practice, learned knowledge beyond textbooks and the application of knowledge in life. What's more commendable is that in the process of joint exploration and study, we not only learned knowledge, but also exercised our hands-on and brain-thinking abilities and realized the importance of collectivity. It is good for our future study and life.