Science Secrets-bead Chain "anti-gravity" phenomenon of large analysis, you have thought of the reason?

Under certain circumstances, a chain may appear to show an inverse gravity, moving like a stream of water flowing in a fountain. The reasons behind this phenomenon have recently been revealed by physicists. This study has significant implications for many of the existing applications, including tethered satellites and space lifts.

Chain technology is one of the most common, ancient and widely used technology, many people think that physicists have fully understood the chain of all. But it's not true.--BBC previously disclosed a small video (video link) that was shocked by more than 2.5 million viewers, many of them physics professionals.

This video shows the phenomenon, even at home can be easily repeated-only need a long enough bead chain chain, and placed it in a beaker-like container, pull up the bead chain at one end and put it down. You will observe that the bead chain is not simply "flowing" to the ground by gravity, and that the chain moves spontaneously upward during the whole movement, just like a fountain sprays water.

Although it is known that the weight of the chain falls down, scientists do not know why the chain leaps before it falls. "We are aware that we are doing an interesting study. "This month, John Biggins, a physicist from Cambridge University, and colleague Warner (Mark Warner) published a paper on the phenomenon of John Bukings in the Royal Society report A.

Some viewers think the chain itself has some magnetism after watching the video, but more than Kings it is clear that the phenomenon has nothing to do with magnetism. "Many people speculate that the bead chain leaves the container under an upward force, but eventually it falls on the ground," he said. Therefore, the bead chain will appear a period of upward displacement, because this bead chain takes a period of time to reverse the direction of rotation, like a toss of the ball up after falling. "than Kings said. However, these speculations are incorrect. Bukings the difference between the throwing motion of the ball and the "Bead Chain Fountain". The top throw of a ball is a deceleration process that reaches the vertex at zero speed. But the bead chain goes up and down at the apex, and the speed of ascent and fall remains the same.

The researchers ' calculations suggest that the forces that drive the chain upward are not from the bead chains that have been lifted out of the container, and they calculate that the push force eventually comes from the part of the bead chain that remains in the container. "The thrust from the container is the main reason, which is surprising to many people," he said. "than Kings said.

The idea of the experiment was to use such a video to teach high school physics. "We think it's cool to go through this, and we should figure out the rationale behind this and ask high school students about it," he said. "However, we soon found that the set thinking about chain movement did not explain why the bead chain would soar," said Kings. To explain the problem, we must review the golden rules of classical mechanics. ”

The key to figuring out the source of this external force is to understand the nature of the bead chain. In essence, these bead chains are actually a series of connecting rods. Imagine a pole being horizontally placed in a container, waiting for the movement to follow. Then one end of the pole receives an upward pull, which comes from the part of the bead chain that has been detached from the container. If it is only a pole, then the force of the end will rotate and lift up, the other end is turned downward. But because in the bead chain, each short pole is connected with other poles, so the other end of the rod will be the elastic from the container or other poles, and this rebound provides an irregular upward thrust. "It is very rare for primary and secondary school students to have the ability to understand real scientific results, but we believe they can understand the experiment," he said. "than Kings said. The Bukings explains the thrust source that makes the bead chain rise. Because the pull from one end of the short rod will rotate the short rod, the other end of the short rod presses the plane and the plane provides the corresponding elasticity. Bukings added that if the chain is constructed of beads with long elastic ropes (as indicated) rather than Lianqi, then the phenomenon of "bead-chain fountain" will not occur.

Although researchers have studied the experiment only out of curiosity, the results may be "instructive to engineering," says Kings: "People use chains and ropes widely in industry and technology." "Textile factories, for example, use spools of yarn for production, and ropes are often used on satellites and spacecraft," he said.

"In areas such as the aerospace industry, people need to minimize the quality and energy needed, and the movement mechanism of chains and ropes may be applied to this." "Kings said:" For example, you need to pull a chain from a satellite to another satellite. Our work shows that when the rope is set, the pull of the rope is supplemented by a thrust, which comes from the place where the rope is stored. "So the pull you need to give is smaller than you originally expected." The force needed to lay the ropes is small, and the work can be done by a smaller, lighter, less energy-efficient motor.

As one of the most likely exotic applications, the project to develop space lifts has been put on the agenda by scientists--a giant elevator connecting Earth and space, containing a long fiber rope that pulls back from space to Earth. To complete this huge structure, the findings of the study may also be helpful.