Bringing the Railway to Daming

Chapter 144: Please allow the hot air balloon launch experiment! [Subscribe]

Zhu Yunwen started to act cute again, but Liu Kuan had already become immune to it and was not affected.

He smiled and said, "What you said is only one and a half - how did we define buoyancy before? The vertical upward force on an object immersed in a fluid is called buoyancy."

"The feathers are fine. A kite is pulled up into the sky by someone, and it's actually affected by three main forces: its own weight, the wind, and the tension transmitted by the person through the silk string."

"Although there is air buoyancy, it is very small and it is extremely difficult to balance the weight of the kite alone, so it is only counted as half."

Because no one in this time and space understood natural science better than Liu Kuan, and there were no restrictions on his education system, so although he also made lesson plans for his natural science classes, when he actually taught they were inspired and he was not bound by the lesson plans written in advance, with details and omissions as he pleased.

The advantage of teaching in this way is that he is engaged in the lecture and the students are also engaged in the lecture - because it is like chatting and listening to a story.

There are actually more disadvantages. For example, the scheduled content of a class is often not completed. If Liu Kuan had not deliberately controlled it, he might often jump from one topic to another.

The topic of air buoyancy was intentionally extended by Liu Kuan from his previous buoyancy topic.

Zhu Yunwen was a little disappointed when he heard that his answer could only be considered one and a half.

Liu Kuan then continued, "Since you described the first phenomenon well, I'll give you two extra credits. Sit down—can the other students come up with other air buoyancy phenomena? The more typical, the more points you'll get."

If you ask about the buoyancy phenomenon in liquids, most students in the university can list one or two.

But when asked about things related to air buoyancy, most students would find it difficult to think of anything other than feathers, leaves, birds, kites, etc.

But under Liu Kuan's expectant gaze, one person still raised his hand.

"Okay, Zhu Tan."

Zhu Tan stood up and smiled confidently, "Teacher, I think the Kongming lantern is a typical example of air buoyancy."

Kongming lantern?
When the other students heard this, they suddenly realized it and then started to feel annoyed, wondering why they didn’t think of it.

Liu Kuan clapped his hands and said with a smile, "Excellent! Kongming lanterns are indeed a typical example of air buoyancy! Zhu Tan gets 5 extra points!"

He then gestured for Zhu Tan to sit down, and he took out a large picture of a Kongming lantern that Chunlan had drawn in advance from the teaching aids he brought with him, and hung it on the blackboard.

"Let me first share a little knowledge with you - although the Kongming lantern is named after Zhuge Liang's calligraphy, there is currently no strong evidence to prove that it was invented by Zhuge Liang."

"Because Kongming lanterns are also known by other names, such as sky lanterns, prayer lanterns, and so on. As for the period when they appeared, it should be between the end of the Later Han Dynasty and the Five Dynasties."

"By the Song Dynasty, there was already a custom of lighting lanterns on major festivals such as the Lantern Festival and the Mid-Autumn Festival."

At this point, Liu Kuan asked, "Schoolmates, I think everyone has released a Kongming lantern before, right?"

Except for Zhu Zhi and Zhu Yunwen, all the other students nodded and said to let it go - this made the two little ones very envious.

Liu Kuan then asked, "Have you ever thought about why a Kongming lantern can only float into the air after it is lit and burns for a while?"

This time, Zhu Tan, Zhu Xiongying, Zhu Chun, Zhu Bai, and even Zhu Ying all raised their hands.

Liu Kuan called out Zhu Xiongying's name.

Zhu Xiongying stood up and said, "Teacher, it must be due to the effect of buoyancy!"

"Student Zhu Xiongying, your answer is a bit off topic. Think carefully about the teacher's question."

Zhu Xiongying frowned and thought about it, and soon he came up with an answer. "Teacher, maybe it's because the burning oil or candle increased the buoyancy of the Kongming lantern, which is why it slowly rose into the air!"

Liu Kuan smiled and nodded. "Good answer, 5 points. Also, I have another question for you: why does burning increase the buoyancy of a Kongming lantern?"

"this···"

Zhu Xiongying thought hard, but couldn't come up with a reliable answer. Liu Kuan gestured for Zhu Xiongying to sit down and said, "In today's class, we will explore how Kongming lanterns float into the air..."

For the children in the main hall, Liu Kuan’s classes are so exciting and attractive that they almost always end before they know it.

This class was the same, and it ended before I knew it.

“Natural science not only emphasizes the observation and study of various phenomena, but also seeks to apply the principles contained therein to benefit the people and the country.”

"Now let's think about this: besides using Kongming lanterns to pray for blessings during festivals and convey military intelligence in certain specific scenarios, what other uses can they have?"

At this point, Liu Kuan smiled and said, "Everyone can let go of their imagination and think boldly."

The students immediately frowned and began to think hard.

Two or three minutes later, when the class was about to end, Liu Kuan asked, "Those who have ideas, please raise your hands."

This time, except for Zhu Ying, no one else raised their hand.

Liu Kuan was quite surprised, but still called out Zhu Ying's name.

Zhu Yi stood up and said excitedly, "Teacher, I think we can make a giant Kongming lantern so that the buoyancy of the air it holds can not only support itself, but also carry a person!"

"In this way, when the wind direction is right, the soldiers can ride on the huge Kongming lantern and fly into the city, or fly over the enemy's head and shoot from a high position to defeat the powerful enemy!"

Liu Kuan nodded. "Student Zhu Ying's idea is indeed bold and unique. So, can this bold idea be realized?"

"This is the homework for this class—after we go down, through hypothesis, inference, and even experimentation, explore whether it's possible to create a giant Kongming lantern capable of carrying people into space!"

"Okay, get out of class is over!"

"stand up!"

"goodbye teacher!"

"goodbye students."

···
Liu Kuan left the main hall but did not leave the palace. Instead, he came to Fengxian Hall and took the initiative to meet the emperor.

After the eunuch informed him, he was quickly allowed into the palace.

Old Zhu sat high on the dragon throne, looked at him and said, "You rarely come to see me, kid. Tell me, what's the matter? It can't be that there's something wrong with the train test run, right?"

Liu Kuan was speechless after hearing this, thinking to himself, "Old Zhu, can't you hope for me to do well? Besides, that was the first train of the Ming Dynasty."

He said politely, "Your Majesty, I came here mainly to apply to lead the students in a special experiment."

"Experiment?" Old Zhu asked curiously, "What experiment?"

Liu Kuan said: "Hot air balloon launch experiment!"

Without waiting for Old Zhu to ask, Liu Kuan took the initiative to explain what a hot air balloon is. Finally, he said, "Your Majesty, if the Ming Dynasty had a mature method of making hot air balloons, it could be used for military purposes."

"For example, if two sides are facing each other on a plain, our army can launch a hot air balloon and have soldiers with good eyesight wear telescopes to act as observers on the balloon, so they can keep abreast of the enemy's movements."

"In addition, if the wind direction, location, and other conditions are suitable, we can also send a small number of soldiers to take a hot air balloon and launch a fire attack on the enemy camp from the sky!"

　Second update.

　　Good night~
　　
　　
　
(End of this chapter)