Transmigrated into a female county magistrate during a famine, leading her country to prosperity

"Scale! It's a scale! Yes! We have been using scales since we were young! When I was a child, I wondered why such a small weight weighed five pounds?"

"This is really too commonplace. Now think about it. The weights on both sides of the scale should have a reason!"

Liang Fu's breathing stagnated when he heard this, and he immediately began to think.

scales......

Yes! It’s a scale!

Isn’t the scale a typical example of “small investment for big gain”?

But... Liang Fu was still a little confused.

The scale is on a pole, like a hoe. The markings and weights of the scales are not fixed, but are obtained after countless experiments. The weights and styles of scales and weights in different regions are also varied.

Tools like windlasses look nothing like scales!

But Lord Shen said that they have similarities...

Liang Fu looked at Shen Zheng. He always felt that Shen Zheng had thoroughly understood this "mechanics" a long time ago, but he had no evidence.

Then, Shen Zheng carefully explained the principle of leverage to them: "... the lever, fulcrum, power, resistance, and the lever arms of both parties together form a force. With these, a lever system is formed. The length of the lever arm will directly determine the strength of both parties."

Just one sentence made everyone confused.

"If you still don't understand, please refer to this hoe and this scale."

……

The hoe never thought that it would be touched by so many people on the same day.

He touched it up and down and found it clean.

Shen Zheng did not explain the formula of the lever principle, but just let them feel the mechanics first.

If she suddenly threw out a formula, everyone present would probably be confused.

In fact, the lever principle is easy to understand without applying a formula, after all, it is closely related to life. But within a quarter of an hour, many people had figured it out, and the atmosphere was very lively.

"Chopsticks! Aren't chopsticks also levers? When we use chopsticks to eat, our hands are clean and it brings us convenience, but it is laborious!"

"That's right! That's right! But chopsticks... the fulcrum is our fingers, so which one is the driving force and resistance that Mr. Shen mentioned..."

As soon as this question was asked, the craftsmen and students who had finally gotten the hang of it were stumped again.

Shen Zheng didn't expect that they would mention an "atypical" lever as soon as they opened their mouths - because the resistance of the chopsticks is the friction of the food on the chopsticks.

But she didn't speak to explain.

Now she opened her mouth and began to explain to them what friction was. If she continued like this, today would not be enough.

There is also a saying: "The master can only lead you to the door, but the practice depends on yourself."

It would be a good thing to let them explore and study on their own first so that they can have a general idea of ​​it.

Liang Fu and Qiao Lao did not join in.

After all, they are two veterans, and their comprehension ability is a little better than that of the newbies.

Liang Fu put his mind back on the well windlass. Slowly, the windlass that had shrunk into a lump on the ground was gradually "straightened out" in his mind and turned into an irregular weighing beam.

The more he understood, the more he felt a sense of clarity he had never experienced before swept over his heart.

He asked Shen Zheng, "Lord Shen just mentioned the scale. Is the well pulley actually an evolution of the scale?"

"Your Excellency is wise." Shen Zheng nodded and continued to explain science to Liang Fu and Old Qiao. In short, she was not afraid that the two would get dizzy.

"Levers can be divided into three types: low-effort, high-effort, and equal-effort. And the well pulley in front of us..."

"Master Shen, please wait a moment."

As Shen Zheng was talking, Liang Fu took out a pen and paper like a magic trick, and said seriously: "Teacher Shen, we can start now."

"......" Shen Zheng looked choked.

Even Liang Fu started to use this trick.

Although she was helpless, she subconsciously spoke in a more formal tone: "The well pulley evolved from the lever, which can be called a deformed lever. Its principle is similar to that of a lever. The one in front of us is an 'equal force lever'."

Liang Fu quickly wrote down a few words on the booklet, then followed Shen Zheng's gaze and asked, "How do you tell the difference?"

Shen Zheng patiently coaxed them: "Please take a look first. Where is the 'lever fulcrum' of this well pulley?"

Almost at the next moment, Liang Fu and the others looked at the axle together and answered confidently: "The center of the axle is the fulcrum, and the input and output forces will act directly on it."

"Where do the power and resistance when pumping water come from?" Shen Zheng asked the old question again with evil intentions.

The surroundings suddenly became quiet, and everyone who couldn't figure out the "chopstick principle" gathered around, not wanting to miss this ready-made lesson.

"Power is the strength of our hands when we pump water, right?"

"I don't think so. It's too obvious. Lord Shen just said that the well pulley is a deformable lever!"

"I think so! And Lord Liang just said it, the hand crank is 'force'! No matter how things change, they still remain essentially the same!"

They talked in a low voice, but their eyes were on Liang Fu and Qiao Lao, and they all wanted to know the answer from the "big boss".

"I still think...the power is the force transmitted from the handle to the handle." Liang Fu was unmoved by the trap set by Shen Zheng and still insisted on his answer.

He looked at the well pulley in front of him carefully, and a simple force arm diagram slowly emerged in his mind. "As for what Lord Shen just said, the 'power arm' that determines the power size is... the length of the handle."

He grasped the point immediately.

"I also think what Lao Liang said is right." Old Qiao stroked his beard and measured the length of the handle with his hand. "It's just like a scale. The longer the 'power arm', the less force is required. And vice versa."

After he finished speaking, he looked at Shen Zheng and said, "Am I right?"

This "seeking praise" look made Shen Zheng laugh. She nodded and said, "Yes, but not entirely."

Mr. Qiao's face fell immediately, "What's wrong?"

He frowned and thought hard, isn't it clear? Isn't the "power arm" the condition that determines the amount of power required?

"Because this is a lever." Shen Zheng placed his hand on the well pulley. "The lever is to balance the forces going in and out. So power and power arm alone are not enough. Resistance and resistance arm are also crucial."

Mr. Qiao suddenly realized.

"The resistance is the weight of the bucket and the water, and the resistance arm..." Liang Fu looked at the center of the axle and gave the answer after a moment: "The resistance arm is the length from the center of the axle to the bucket."

"Is this a resistance arm? Why?"

Most people are puzzled, "They are not in the same line, why are they the same lever arm?"

"Pa pa pa——" Shen Zheng clapped her hands.

She really admired Liang Fu's knowledge of everything.

He even figured out the resistance arm of the well pulley without knowing the mechanical formulas or diagrams.

Just like before, when he had no idea about the principle of lever, he could say “the key to saving effort lies in the handle and the shaft”.

The reason why Shen Zheng called the well windlass a "deformed lever" before is because its lever arm is difficult to find, which will inevitably confuse beginners.