2020-07-15

Why doesn’t the bicycle ride down? Scientists have been thinking for 200 years, and it is still an unsolved mystery

By yqqlm yqqlm

Overview of human life style, 200,000 years ago and 100,000 years ago, almost no change; 600 years ago and 500 years ago, there is no much change. And if you compare it now with 100 years ago, it can be said to be a radical change.

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​Why is there such a big change? In fact, this is thanks to the help of technology. After nearly a hundred years of practice and summary, mankind has long realized that technology is the first productive force, and every progress of mankind cannot be separated from the promotion of technology.

However, the development of science and technology is essentially the development of science, because technology is actually a concrete reflection of science in the material world. If science and technology are regarded as a high-speed car, then science is the steering wheel and engine of the car, which points out the direction and provides power for the development of technology.

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Although human With the help of science, I learned about the world and learned many mysteries in the universe, but science is not omnipotent. In our daily life, there are many common physical phenomena that science simply cannot explain, such as a very”simple” The question-why the bike won’t fall down when riding.

Maybe many people will be very surprised by this. If you know that bicycles have been invented for two hundred years, how come you don’t know the principle? However, this is the case. Scientists have been thinking about this”simple” problem for more than 200 years, but it is still an unsolved mystery.

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Just connect One of the world’s most authoritative academic journals, Science, has published several papers on this issue.

Of course, although I did not understand the exact reason why the bicycle will not fall down, this group of scientists who can understand the Big Bang still narrowed the possible reasons to a limited number. aspect.

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First This may be the”gyro effect”. In the explanation of bicycle stability, this statement is most widely circulated. Many popular science books like to use this method to explain why the bicycle does not fall down.

Simply put, when the front wheel of a bicycle rotates, its own centrifugal force will keep it balanced, which is like a high-speed spinning top.

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The top is in In the process of high-speed rotation, it will always surround its rotation axis and maintain the inertia in the direction of rotation, so that it can always rotate under external force.

The second possibility is”centrifugal force effect”. In 1948, the famous mechanics experts S.P. Tiemu Xinke and D.H. Yang, in their co-authored”Higher Dynamics”, also explored the problem of bicycles maintaining self-balance.

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SP in the middle is SP Timoshenko

They think that when the bicycle leans in a certain direction, the cyclist will turn the front wheel to the inclined side. Because the front wheel has changed, but the kinetic energy of the forward is still, the bicycle will Moving along the inclined circle where the front wheel is located, the centrifugal force generated at this time will straighten the bicycle and maintain its balance.

The third possibility is the”caster effect”. In 1970, the British chemist and writer David EH Jones published an article in a general scientific magazine at the time, stating that he invented a bicycle that did not use the”gyro effect”. But this car can drive normally and maintain its own balance.

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David ·Junsi’s method is very clever. He added a wheel of the same size and thickness to the front wheel of common bike. During the movement, the added wheels and the original wheels rotate in opposite directions, but the rotation speed is the same, which basically cancels the balance brought by the”gyro effect”.

His ingenious design was very inspiring to later researchers, because he proved with facts that the reason why the bicycle can maintain self-balance is nothing more than the simple”gyro effect”. Relationship, or not the main reason.

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From this Relevant scientists also put forward a new idea. When the bicycle produces a tilt angle during sports, the front wheel also has a trail of the front wheel, so the rear wheel will also produce a similar tilt angle to the tilt direction. In this case The centrifugal force will straighten the bicycle.

As a result, even if no one controls it, the bike can be pushed out directly, and the bike can maintain self-balanced exercise for a period of time.

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In comprehensive After the above three possibilities, a fourth possibility appears. This possibility believes that the gyroscopic effect, the caster effect and the centrifugal force alone cannot balance the bicycle. Only these three forces are combined, that is, there is a subtle connection between them. It is this connection that enables the bicycle to Balance will not fall.

Simply who comes, when an object has a speed, it will have a tendency to keep its speed unchanged. When the bicycle is fast enough, the kinetic energy tilted to both sides will be less than the kinetic energy generated by its own speed, so we only need to give the bicycle a little force, and it can always maintain balance.

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And when When the bicycle turns, the dumping ground force is less than the centripetal force generated, so it can also maintain relative balance when turning.

When the bicycle is not being applied with external force, the speed gradually decreases until it stops, because there is no force to limit the dumping force, and it achieves a balance with it, so it needs people to support it with legs With the entire bicycle, the balance with the dumping force is achieved so that the bicycle will not fall to the ground.

Of course, these analyses are just a few possible answers, not the standard answer to this question. If it is really so simple to be answered, the balance of the bicycle will not leave the scientific community helpless for more than 200 years. It is still an unsolved mystery.