No illness?Two steps without illness

Recently, I was busy with scientific research. I was sitting watching the computer most of the day, but I had back pain for a long time. I couldn't help but go to the hospital for two days.

Do I think this is not a joke, can young people get this disease? Proper misdiagnosis. I said that my waist was not sick. The doctor said that I was sick. I asked him how to prove it. I saw that he waved his little hand and said, "No illness? Two steps to take two steps."

Just leave, just want to stand up from the chair, and suddenly the legs are numb. The interns was surprised: "Is he numb before he leaves?" The doctor smiled slightly and said, "You suddenly you are numb."

After experiencing this, I know if I have a disease, the key is not whether I really take two steps, but whether I can really take two steps, that is, "want to take two steps" and "capable Two steps "Sub -relationships.

The trend of "you want to take two steps" is not essentially a famous displacement in mechanics. As the saying goes, you want to go, but you do n’t have to go, leave, and do n’t completely leave.

In order to explain the characteristics of the deficiency displacement in detail, I recalled the day after the consultation, the doctor asked me three questions:

This shows that the deficiency displacement is infinite, that is, you can only go a little, not too much.

That is, the deficiency displacement is not arbitrary. To meet certain constraints, go to Erxian Bridge, and can only go to Hua Avenue.

Then the deficiency displacement does not actually exist, but it is imagined out of thin air.

Therefore, virtual displacement is the infinite non -actual displacement that meets the constraints. Then the problem is now, how is the deficiency displacement associated with the illness? First of all, we all know that people's actions are determined by will. We first have two steps to take two steps, and then our body will respond to actual position changes, that is,:

Change of physical condition is proportional to the deficiency displacement

I have said that the deficiency displacement is infinite, and I can only take a little bit, and the physical condition can only change a little. Next, according to the basic theory of medicine, people who are not sick eat spicy and spicy, they can sleep and go, that is,:

I have sick → I want to go, but I can’t walk = there is a virtual displacement, but the physical condition has not changed

Therefore, if a person is sick, it means that the physical condition changes to zero. This time I finally understood why the doctor said "two steps without illness", which is essential to see if you can leave when you want to leave. It must be sick.

As a complex mechanical system, people must obey the corresponding mechanical principles. The above discussion about the two steps is essentially the most basic mechanical principle -the principle of virtual skills. We say a mechanical system

Deficiency is proportional to the deficiency displacement

For some particularly important states, such as balance state, satisfaction:

Balance → For any deficiency displacement, the virtual power is zero

This is the most general expression of the principle of virtual skills. Promote to any function or general letter, we know:

The independent variables of the function are numbers or arrays.

Then there is:

Infinite changes in functions or generalized letters are incredated.

therefore:

Destroyer → For the infinite changes of any independent variable, the infinite changes of the function or general letter are zero

In summary, the idea of ​​"two steps without disease" almost elaborates the essential thoughts of differentiality and change. The two steps to take are equivalent to a test. In the future, when you encounter a mechanical system you want to study, you can say similarly: "Balance? Balance two steps." Let the system's independent variables "take a little bit" to see the changes in the total energy of the system. If the total energy does not change after "a little bit", it means that this system is balanced.

After writing so much, I suddenly found that I was sitting for a long time. I hurried to move, twisted my waist, and took two steps, or I was really sick.

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