In the Ming Dynasty 1498, my restaurant connects two worlds.

Chapter 108 The Crown Prince's Physics Initiation (Part 2)

Upon closer inspection, it is a set of gears made of boxwood meshing, with a hand crank attached to the side.

Song Shen turned the crank himself, and the gears turned in sequence, causing a wooden pole to rise and fall, making a slight "click" sound that was particularly clear in the quiet morning.

"Lord Song, what is this?" Zhu Houzhao leaned closer, his breath swirling between the gears.

"This is a model of a waterwheel," Song Shen explained. "Even though it's the dead of winter and the water is frozen, the principle remains the same."

"Young master, please observe: when the large gear rotates once, the small gear rotates several times, resulting in less force but faster speed; conversely, if the small gear drives the large gear, the force increases but the speed decreases. This is the wonder of the exchange between 'force' and 'speed'."

"Farmers rely entirely on this principle to draw water for irrigation during spring plowing and summer weeding."

"Lord Song, may I give it a try?"

"Young Master... wait a minute!" Wang Shu hurriedly stopped him. "Lord Song, is this... safe?"

"It's perfectly safe and sound, Mr. Wang, why don't you give it a try?"

Wang Shu stepped forward and, following Song Shen's instructions, tried shaking it.

"Mr. Wang, how are you?"

"Yes, it's truly exquisite!"

"My turn! My turn!"

"Young master, please. Take your time."

Zhu Houzhao reached out his little hand, first touching the cold gears, then trying to crank the handle. As he felt the changes in resistance from different combinations, a look of surprise flashed in his eyes: "So strength can change like that! Doesn't that mean that as long as the gears are matched well, even a child like me can lift a thousand pounds?"

"Indeed! Young master, you are wise!" Song Shen praised, "This is the principle of 'lever' and 'wheel and axle.' Using minimal force to move a great weight—this is no exaggeration."

Song Xiaoyi, standing nearby, chimed in quietly, "Young master, this is the essence of investigating things to acquire knowledge. Sages teach us 'benevolence, righteousness, propriety, and wisdom,' while heaven and earth teach us 'strength, heat, light, and sound.' Neither should be neglected."

"Without understanding the hardships of the people's lives, it is difficult to implement benevolent governance; without understanding the principles of nature, it is difficult to achieve good governance."

Zhu Houzhao seemed to be deep in thought. To govern the country, one needs not only benevolence but also "knowledge."

After examining the first instrument, Song Shen beckoned again, and the craftsmen brought out a small catapult model.

Song Shen pointed to the lever arm and counterweight box, saying, "This thing is called a cannon. It uses the force of a heavy object falling to launch stones at the enemy. A longer arm means farther range, and a heavier counterweight means greater power, but it needs to be balanced, otherwise it will easily break."

To help him understand, Song Shen instructed the craftsman to set up a target on the snow in the distance of the courtyard, load it with mud balls, and adjust the angle. "Young master, please try it. This cannon is very light and not dangerous."

Zhu Houzhao looked up at Wang Shu, and Wang Shu looked at Song Xiaoyi. Song Xiaoyi thought to himself, "Why are you looking at me? That's my father. How could he harm the Crown Prince? My whole family is just a matter of life and death."

"Young master, I am aware of this cannon; it is harmless. Go ahead."

Zhu Houzhao stepped forward as instructed and, under Song Shen's guidance, personally pulled the mechanism. With a "whoosh," the mud ball pierced the cold air and struck the snow target, splashing up a cloud of white mist.

"Yay! I hit it!"

"But why does the mud ball fly in a curved path instead of straight?" Zhu Houzhao pressed.

"Young master, please look, this is a parabola." Song Xiaoyi squatted down and drew an arc on the snow: "All thrown objects follow this path. This is the angle; the range is greatest at a forty-five-degree angle. This principle can be calculated, measured, and verified."

After Song Xiaoyi finished speaking, he gathered up a pile of snow from the ground, made several snowballs, and squeezed them tightly. "Young Master, take another look."

Song Xiaoyi threw the snowballs at different angles, instructing Zhu Houzhao to watch where they would land.

The young eunuch Wei Bin was very perceptive. He pulled Gu Lan along to gather snow, make snowballs, and pile them at Zhu Hou's feet.

Zhu Houzhao picked up the snowballs one by one and threw them repeatedly to verify the relationship between angle and distance.

When he discovered that 45 degrees was indeed the furthest point, he clapped his hands and laughed, "Amazing! This is much more interesting than reciting the Thousand Character Classic!"

"Young master, be careful what you say," Song Xiaoyi quickly reminded him, then gestured towards Wang Shu with his chin. Zhu Houzhao chuckled and stuck out his tongue, not daring to look at Wang Shu.

Wang Shu pretended to stroke his beard and look up at the sky, but his peripheral vision kept following the snow target. His withered hand in his sleeve curled up slightly, and his Adam's apple bobbed quietly. In the end, he suppressed the urge to step forward and try.

Then, Song Shen led them into a secret room.

The room was warm and cozy. A row of newly cast firearms was displayed against the wall. Song Shen picked one up and pointed to the barrel, saying, "Young master, do you know that we are testing rifling? Rifling is the spiral grooves carved inside the barrel. When the projectile is fired, it spins like a top, making its flight more stable and its range longer."

Song Shen traced a spiral on the gun barrel with his thick fingers, his burly body tilting slightly with the movement. Song Xiaoyi quickly lowered his head and covered his lips, trying to suppress his laughter, almost bursting out laughing.

Why does the projectile remain stable after it spins during firing?

This is the principle of conservation of momentum. A rotating object's axis is not easily deflected. Like a spinning top, the faster it spins, the more stable it becomes.

.

Zhu Houzhao listened intently.

Emerging from the secret chamber, the sun was rising higher outside, its light reflecting off the snow. Gu Lan reminded her that it was time to return to the palace.

Zhu Houzhao was reluctant to part, and before leaving, he solemnly bowed to Song Shen, saying, "Thank you, Lord Song! I feel that these opportunities for good fortune are even more important than the Analects!"

On the return journey in the carriage, Zhu Houzhao wrapped himself tightly in his fur coat, but was wide awake. He kept asking, "Master Song, can a parabola be calculated using counting rods? Can the axis of a rifling be drawn? How should the number of teeth on a gear be matched to minimize effort?"

"Your Highness's questions are all permissible," Song Xiaoyi replied with a smile. "I have already ordered people to search for fragments of the *Mo Jing* and geometric atlases from the Western Regions, and have arranged for craftsmen to make simple instruments for Your Highness's experiments. This field of study is what Westerners call natural philosophy," a discipline that explores the fundamental principles governing the workings of heaven and earth.

Zhu Houzhao nodded vigorously. "So there are still so many truths in this world that I don't know."

In fact, deep within this ordnance bureau, there are gunpowder workshops and repeating crossbow workshops that are classified as top secret and cannot be entered without special permission.

The carriage rolled over the snow and headed towards the palace.

That evening, in the palace.

The young eunuch Wei Bin directed other eunuchs and palace maids to make snowballs and hand them to Zhu Houzhao. The crown prince repeatedly tested the relationship between the force, distance, and angle of the snowball throws.

However, Crown Prince Zhu Houzhao selectively forgot his "homework" from the first day of his study trip. Wei Bin, on the other hand, kept in mind Song Xiaoyi's instructions, but the Crown Prince was having so much fun that I didn't dare to remind him.

No, the Crown Prince is reviewing his daytime classroom assignments!

Nanchizi Street, Wang Shu's residence.

The head steward directed a group of servants and maids to make snowballs and hand them to Wang Shu.

"Where is the master?"

"I don't know what's gotten into the master, he's not sleeping at night, he's playing with snowballs in the yard."

Beichizi Street, Song Residence.

Song Xiaoyi drank cola and played chess with Tang Bohu in the warm pavilion, watching Gu Lan and Xu Zhenqing playing with snowballs in the courtyard outside the window.

After returning, Mu Bin pulled Song Xiaoyi and Gu Lan aside and asked, "Brother Xiaoyi, what are your plans for tomorrow?"

"First investigate things, then consider people's livelihoods. Tomorrow I'll go with my mother to the Donghuamen vegetable market to buy groceries."

"Sigh..." Mu Bin sighed deeply, his brows furrowing deeply. "Alright, I'll go and make the arrangements first."