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

Shen Zheng took the roller off the donkey's back and compared it to a millstone.

"Everyone, look." Shen Zheng stood behind the roller and pushed it from behind. "Compare this roller to a stone mill. I will push the stone mill with all my strength."

She didn't use much force, so the roller only rolled slowly in one circle after being stressed.

"The force that the millstone received when it started to roll was transmitted from my hand."

Everyone looked at Shen Zheng's hand and nodded.

They know this.

"When the stone mill is subjected to force, it starts to roll. The direction in which it starts to roll is the direction in which the official applies force, which is the tangent direction of the rolling force source."

As she spoke, Shen Zheng explained to them again what tangential force was - roughly speaking, it can be understood as the force along the direction of movement.

Liang Fu's eyes flashed, and he seemed to understand something.

But he still didn't say anything. Instead, he listened carefully to every word from Shen Zheng's mouth and watched every movement of Shen Zheng's hands.

Shen Zheng patted the roller, looked at them and said, "Just now Cheng Yu said that the biggest disadvantage of using a stone mill to tamp the ground is not that the livestock will damage the ground. It is that the force generated by the livestock dragging the stone mill will almost only have a shear force at the moment when the stone mill touches the ground. As for the force applied to the ground by the stone mill afterwards, most of it actually comes from its original gravity."

In fact, these examples can be found everywhere in life, but Shen Zheng explains them from the perspective of mechanics, which makes them inevitably more complicated for people who have not been exposed to system mechanics.

Although complexity is complex, it also has its benefits.

If you can fully understand the concept of "complexity", you will be able to apply it to other situations.

Except for Liang Fu and Mr. Qiao, many people looked puzzled.

Shen Zheng sighed in her heart, today was indeed a day to be accompanied by science.

I have just finished discussing chemistry, and now I am discussing physics.

Oh, by the way, I taught mathematics at the county school this morning - it is true that mathematics, physics and chemistry are inseparable.

Liang Fu was still thinking carefully about Shen Zheng's words.

Shear force...Direction of force...

He found it difficult to describe the feeling at the moment - it was as if he had an old friend, but he never knew the other person's name, so the other person was extremely hazy in his eyes, and he was always worried that the other person would leave without saying goodbye and they would never see each other again.

Now that the word "qieli" came out of Shen Zheng's mouth, Liang Fu seemed to know the name of his "old friend" and the address of his "old friend", and his relationship with the other party became closer.

He got it!

Liang Fu's mind was working quickly, and he was the first to show off to Old Qiao: "Old Qiao, I understand what Mr. Shen meant. I wonder if you can understand it?"

So Qiao Laoming doesn’t understand?

I understand half of it, but not completely.

But at this moment, how could he admit defeat?

"Of course I understand." He rolled his eyes and looked at his most proud disciple: "I just wonder if you understand it?"

"Disciple understands!" Cheng Yu stepped forward excitedly, "Master Shen, I wonder if my understanding is correct? Previously, I chose the stone roller for the purpose of pressing the ground, but the stone roller was rolled by the livestock, and the direction of the force was wrong. It was a waste of force for pressing the ground!"

He was right, energy could be wasted.

This has always been a rather general concept that craftsmen have used when building tools.

When "tools" were first created, their purpose was to "save effort" and "convenience". In the hands of one person, a tool can produce the effect of three, five, or even ten people.

That's labor saving.

While it can save energy, there will naturally be "wasted" energy in the process of life.

“Pa pa pa—” Shen Zheng clapped her hands and praised him generously, “Smart, it’s okay to understand it this way. In fact, this principle is very simple and very common, but because it is so common, most people will get used to it and won’t pay attention to it.”

After Cheng Yu's explanation, many people present fell into deep thought.

I seem to understand it, but it also seems like I’m still a little bit off.

Shen Zheng gritted her teeth as she looked at those faces that were eager to learn.

I have to learn mathematics, and I will have to learn chemistry later, so I might as well learn physics as well.

Today, Mr. Liang Fuqiao and others are here, so she can take this opportunity to give a small physics lecture and lay the foundation for the physics classes in the county school in the future.

Shen Zheng stood at the front of the crowd. Facing her were craftsmen such as Liang Fu, Old Qiao, and Cheng Yu, as well as the students from the county school who had just "followed" her.

Behind her were Wu Quan and others who were working hard.

They have clear division of labor in unloading soil, mixing soil, laying and tamping the ground layer by layer.

But if you look closely, you can also find that their ears are almost erected to the sky - they really want to listen, but dare not show it too obviously, what should they do?

It’s not that they are being coy, but what kind of people are standing on the opposite side?

Not to mention the two officials, Lord Shen and Lord Liang, even the students in the county school and the craftsmen are all smart ones selected from hundreds. How could they have the nerve to "take the same class" with them openly? Isn't this belittling the smart ones?

Shen Zheng looked around, searching for suitable scientific information within his sight.

"Mechanics is a very magical subject, starting from the basics to the deep end."

She temporarily called elementary physics "mechanics" because for the current Great Zhou, if it can achieve the goal of "saving effort" in using tools and equipment, then this subject can be considered to have achieved initial results.

"First, understand mechanics, then explore force, explore the 'direction' of force, the 'multiplication' of force and the 'loss' of force. As I just said, you will find that mechanics is everywhere in life. And through your exploration, there will definitely be more 'labor-saving' devices invented to benefit the people and promote the progress of our Great Zhou."

A mouthful of pancake was fed equally into the mouths of everyone present.

Liang Fu, Old Qiao and a group of craftsmen were so moved that even the students in the county school were excited by what she said.

In contrast, Wu Quan and the others reacted indifferently, with obvious lack of confidence on their faces.

What can these coolies invent? It would be great if they could not hinder Lord Shen.

"In fact, things related to it have been invented a long time ago." Shen Zheng looked at Liang Fu and Qiao Lao and smiled, "In farming, there are tools such as hoes, axes, plows, and stone mills. In the military, there are arrows, simple crossbows and other equipment. In life, there are also tools such as carriages and textile machines."

Yes.

Everyone nodded. These things didn't just appear out of nowhere, they were improved step by step, right?

Take the hoe used for tilling the land, for example. Isn’t it also an improvement on the plow?

Seeing that they understood, Shen Zheng continued, "The help these tools bring to us is called 'mechanical advantage', and its purpose is to bring convenience."

She never gave up looking for suitable scientific tools in this area, and finally, she found a well.