The four legs of the stool are movable, which means that when people sit on it, the weight will be transferred down along the four legs. In the case of different landing areas of four legs, the rebound force given to these legs by the ground is also different. This is because of the principle of reaction force in mechanics, that is, the acting force and reaction force are equal in size and opposite in direction. People sitting on a stool will have a center of gravity due to the distribution of weight and the weight of the stool itself.
Due to the mobility of the four legs, the center of gravity will naturally change, resulting in a slight change in the position of the stool on the ground. This small change, in the case of different landing areas of four legs, will produce different reaction forces, leading to the stool moving on its own. The principle that the stool can move by itself is to use mechanics and mechanical knowledge to make the stool move naturally under the action of human weight through the interaction between the change of center of gravity and the ground reaction force.
The origin of magic:
The earliest magic record in history is in ancient Egypt, about 2600 BC, that is, more than 4 thousand years ago. /kloc-the huesca manuscript discovered in 0/823 records a magician named Dade who was called to perform for the Pharaoh. He can cut off the goose's head, but the goose with the broken head can still walk, and finally put the head back to the original goose. The record describes that the magician performed the same magic on the pelican and the bull.
But when Pharaoh asked him to perform the same trick on the prisoners, he refused. Temples in ancient Greece also used the principle of magic. For example, when the priest opens the door of the temple, the bellows will blow to the ground and flames will appear on the altar. And talking idols made of bagpipes. /kloc-The end of 0/9th century is the golden age of magic show, and magic shows everywhere are full. The magician wore a formal tuxedo, just like the audience who went to the theater at that time. This is also the origin of the magician wearing a tuxedo to perform.
Some magicians have even become household names. The most famous magician in the early 20th century was Harry Houdini (1874- 1926), a legendary magician who was well-known in the United States. Houdini is good at escape performances, handcuffs, tights, milk cans, China dungeons and the most famous underwater escape. Houdini was also a pioneer in exposing so-called psychics who used magic to deceive the public. People still remember his deeds today.