Future library

"The balance?" Xiang Xin looked at Cheng Jinzhou in confusion and said, "If you are referring to the balance I gave you last time, it is a very good one."

"I know, I know." Cheng Jinzhou happily looked at the content on the ring and said with a smile: "I've been itchy recently and thought about making a scale myself, but I don't understand many things. …”

Xiang Xin showed a trace of disapproval and said: "The balance is something that only professional star warlocks can make. You just need to know how to use it now."

What she actually wants to say is: You don’t even need to pay too much attention to using it.

People who have been taught the greatness of astrology since childhood have a religious fascination with astrology, a religious piety towards rank, and a religious discrimination against the weak...

Clearly feeling this kind of discrimination made Cheng Jinzhou very uncomfortable. He was just looking for a reason at first, but now he was very unhappy with the other party's attitude and said with a sour tone: "I don't think it is so difficult to be a balance. If With enough materials, it can be done easily.”

"Has little knowledge." Xiang Xin said mercilessly: "The balance is not just a matter of placing a horizontal bar in the center and then measuring the weight. The equal distance between the two sides is only the simplest requirement. It also involves many things. Complex mathematics..."

"It's just torque balance." Cheng Jinzhou shrugged and said, "You just want to say that if an object is moved a certain distance, the moment it generates should be the same, so the lengths of both sides of the scale should be equal..."

Xiang Xin's eyes were as round as her bald head.

The so-called torque balance is exactly the principle of leverage. Archimedes said: Give me a lever and I can lift the earth. This refers to the lever principle: Theoretically, if a horizontal bar is placed on the fulcrum, in order to balance the two sections of the fulcrum, the farther away from the fulcrum the farther the bar is from the fulcrum. The place is less laborious.

Ordinary people know from common sense that as long as the lengths of both ends of the crossbar are equal, the two ends can be balanced. However, in actual use, the two sides are often unbalanced. In this case, you need to know the relationship between distance and mass - distance multiplied by mass. It is equal to distance times mass. It is easy to say but not easy to prove.

The main purpose of the balance that can be used is to measure mass, and in order to ensure its accuracy, the most common pallet balance cannot just use weights - weights with an order of magnitude less unit mass (Note 1) are also necessary for measurement - —It uses the calculation formula of the leverage principle.

After being told what she was most proud of, Xiang Xin's sneer subsided. At this moment, she began to admire her master's vision again.

Cheng Jinzhou raised his eyebrows provocatively. Compared with mysticism, he is at the level of a primary school student, but compared with these basic knowledge and the earth's technology that have been refined over time, he can completely defeat primitive people. Remembering that the newly obtained "Mechanical Measurement" was the high-end knowledge of this era, he couldn't help but show it off and said: "Do you know how to determine the position of equilibrium?"

"The weight is quite the same." Xiang Xin has long been familiar with these contents.

Cheng Jinzhou laughed deliberately: "Superficial."

"What did you say?" Xiang Xin's right shoulder began to glow again.

Cheng Jinzhou took a step back and said forcefully: "Do you want to use force to explain the problem?"

Xiang Xin snorted, shook his arm, the light went out, and continued to hold his head high and said: "If you can't tell me something, I will trouble you again."

"How difficult can it be?" Cheng Jinzhou curled his lips, picked up a piece of wheat straw, held it sideways in his hand, and said: "If you want the two sides to be completely balanced, this simplest scale is the same as nothing else. There is no need to discuss it, but If it’s tilted at a certain angle.”

Cheng Jinzhou slowly placed the wheat straw at an angle of 45 degrees from top to bottom and said: "Now you see, the lever is actually at an angle with the ground. The torque at this time is no longer a function of length and mass. There should also be a 45 degree angle. The trigonometric function value of degrees, right?”

Mathematics is the movement of discovering that old methods fail in the constant pursuit of accuracy, then designing compensation methods, and finally failing again.

The principle of leverage is very simple. Humans knew it before BC, but when its application used trigonometric functions, it took 1,000 years of development.

Xiang Xin understood the disadvantages of ordinary scales, but she didn't expect that Cheng Jinzhou also knew about it, and was stunned for a while.

This is a teenage boy! Xiang Xin secretly evaluated whether he was as good as when he was a teenager...

The two looked at each other for a moment, then Xiang Xin raised his chin again and said: "I will bring the Star Warlock materials. If they are not enough, I will buy more. If you can make one..."

"I won't go to Nanling." Nanling is the territory of Nanling County King. Even if there is no Sith Temple and there are two perverted Zhao family, how can Cheng Jinzhou be willing to find it?

"Although I can't change your father's decision, I will persuade him if you can really complete a high-precision balance." Xiang Xin already looked at Cheng Jinzhou with a straight face. Regarding the many skills in the process of making the balance, It is also kept secret in the Star Warlock Association. In other words, she actually does not know how to make a high-precision balance, and the other party can tell the torque balance, which is beyond the scope of ordinary students.

Cheng Jinzhou snorted indifferently and said, "This bet is really light for you, so let me take action."

His hands-on ability is much better than that of a middle school student. A true playboy never worries about exams.

Instead, Xiang Xin raised his head in surprise and began to doubt Cheng Jinzhou's generosity again.

"Okay, I still have something to do here. You can go out first." Cheng Jinzhou pretended to start chasing people away. He did still have 1 Star Alliance point to upgrade.

The momentum was weakening, and the young first-level star warlock couldn't say anything. He left the granary obediently. His attitude of being arrogant at first and respectful at the end made the boys outside look at each other.

Cheng Jinzhou narrowed his eyes and smiled, and said to the ring with a sense of success: "Let's continue."

"30,000 words." Customer service 010 was already impatient with the wait.

"There can't be so many words." Cheng Jinzhou wiped the sweat from his forehead and said, "The star warlock just saw the situation in the granary. He suddenly lost a lot and will be discovered."

30,000 words, but it requires 60 star yuan of food. 6 tons of food, which is 6 cubic meters, can be easily discovered.

Customer service 010 said impatiently: "13,000 words. Are you sure?"

"That's it." Cheng Jinzhou was actually very anxious.

""My Days in Tehran"" Customer Service 010 said in a cold voice: "Congratulations, the Star Alliance level has increased to 3."

Cheng Jinzhou suddenly opened the door of the granary, and the midday sun rushed directly into his face, and a feeling of sudden enlightenment emerged spontaneously.

"The era of mathematics is my era." Cheng Jinzhou thought silently in his heart and nodded silently.

…

Travel weight: When using a balance, the smallest weight can be 1 gram. If it is smaller, daily use will make it inaccurate. For this reason, we use the lever principle to make a larger weight fixed on the balance. , able to display smaller precision, such as 0.1 grams.

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