After writing this big story, He Hongjun moved his fingers and looked up at him, "What you said is so empty, I feel that it's useless. You're telling me a little more vivid."

"To be specific?" Lin Xiyan put down the fan in his hand and said, "Bernoulli's law, a very important law of material force, reveals the basic principle of aircraft takeoff. It was discovered by Daniel Bernoulli, the famous father of fluid mechanics, in 1738. Its formula is like this." As he said that, he pulled out the pen in his hand and wrote it in a notebook. "This formula says that within the range of the fluid, speed is inversely proportional to pressure. That is to say, the faster the speed, the smaller the pressure. What is the concept of speed? Speed ​​is within a unit of time..."

"Wait... stop talking. This law knows me, I don't know it, and it's useless for you to write it down. I don't understand what it means at all? This makes me dizzy than the passage you just said." He Hongjun pointed at the notebook with his index finger, "Don't use professional terms, I don't understand professional terms. You are a teacher who is not qualified, don't you know that it varies from person to person?"

"I have understood what Zhu Bajie is to turn the tables." Lin Xiyan looked at him with laughter and cry, gently stroked his forehead, "Since that's the case," he pulled the notepad to his side, "Put it! Hurry up."

"Oh!" He Hongjun picked up the big palm fan on the table and fanned the two of them.

Lin Xiyan wrote a few strokes in the notebook, "This is a cross-sectional view of the aircraft wing. It has an arc on top and a straight line on the bottom. Which side is above and below is longer!"

He Hongjun scratched his head and thought for a while, "It should be above!"

"Yes!" Lin Xiyan nodded and said further, "So when the air passes through the wings, the flow rate above will force the lower part to be faster. Then a pressure difference will be generated from the upper part and below. This pressure difference is called lift. The aircraft flew into the sky through this lift." Looking at He Hongjun, who was full of mosquito coils, said, "Do you understand?"

"I don't understand!" He Hongjun shook his head like a rattle, "What is pressure difference, lift!"

Lin Xiyan pursed her lower lips and said, "I thought you were at least in the Anti-Japanese University. Now it seems that you can do nothing except reading, reading newspapers, and writing inspections."

"Go to yours." He Hongjun knocked his arm with a fan, "You're just writing a check! I don't need to write anymore."

"How can you feel it with your own eyes?" Lin Xiyan thought for a while, got up and tore off a piece of manuscript paper from the table, and vertically divided the manuscript paper into two from the middle.

"Brother He, if I blow from top to bottom between these two pieces of paper, what effect will these two pieces of paper have?" Lin Xiyan stood at the Eight Immortals table and looked at him, with the two pieces of paper in his hand only a finger away.

"It's all right, you must jump to both sides!" He Hongjun said immediately, and his fingers flew out.

"You come and play." Lin Xiyan handed him two pieces of paper directly.

He Hongjun stood up and said, "Just blow, I must be right."

He Hongjun held two pieces of paper in his hand, lowered his head and blew it from top to bottom.

"Oh! My mother!" He Hongjun shouted, "What's the matter? Why did it get stuck together." He didn't believe in evil and continued to blow, and the result was the same, "It's so magical!"

Lin Xiyan sat down and looked at him slightly, saying, "It's fun!"

"Yes!" He Hongjun nodded.

"I haven't played before!" Lin Xiyan looked at him with a smile and said, "You keep playing."

"Uh..." He Hongjun sat down with a embarrassed smile.

"Uncle, Uncle He, what are you playing?" Zhou Guangming walked over and looked at them and asked.

"Guangming is coming just right, Uncle He will make a trick for you." He Hongjun looked at Zhou Guangming and smiled.

"Okay! OK! What a trick?" Zhou Guangming said to He Hongjun with great enthusiasm.

He Hongjun showed off and blew air between the two pieces of paper, "How is it? Is Guangming fun?"

"It's fun, it's fun, but why do you blow it in the middle? Why don't you look to both sides?" Zhou Guangming looked at He Hongjun with confusion and asked.

"This...that..." He Hongjun was blind and had no idea what to say after a long time.

"Haha..." Lin Xiyan looked at the unlucky He Hongjun and smiled unkindly, "It's time! Let you show off, let's cheat yourself now!"

"Stop laughing, explain it to your nephew quickly." He Hongjun urged to look at him.

"You won't use your brain by yourself! What does this little experiment mean?" Lin Xiyan looked at him and scolded.

He Hongjun looked up at Lin Xiyan, and then looked at the paper in his hand. "The faster the Bernoulli's law you just mentioned, the less pressure. I blew air into the middle of the paper, and the air in the middle must flow faster!" His eyes lit up and said happily, "The pressure on both sides is high, so I sucked the paper into the middle."

"Okay! Brother He." Lin Xiyan gave him a thumbs up.

"That's right, I'm smart!" He Hongjun said boastingly, "but this mind has not been used to it in the past."

"If you really say you are fat, you will pant." Lin Xiyan shook his head and laughed.

"I'll play with it." Zhou Guangming looked at He Hongjun and said.

He Hongjun handed him the piece of paper in his hand, and Zhou Guangming had a lot of fun.

"This is the wonderful part of Bernoulli's law." Lin Xiyan looked at He Hongjun and continued, "If I had replaced it with a piece of paper and I blew it on it, how would it move?" He said, looking at Zhou Guangming and said, "Give me a piece of paper."

"Oh!" Zhou Guangming handed one of the papers to Lin Xiyan, "Auntie."

He Hongjun scratched his chin and said, "Is that simple? You blow air on the paper, as you said just now, the speed on the paper is high and the pressure is low." He gestured with his hands, "Will the paper float up?" He looked excitedly at the hand of paper grabbing Lin Xiyan's hand, and blew his mouth toward him. Seeing the paper float up, his eyes straightened.

Zhou Guangming clapped his hands happily as he saw the floating paper, "It's floating, it's floating."

He Hongjun was playing hard, and he was having a lot of fun.

"Enough, enough, like a child." Lin Xiyan looked at him and shook his head and laughed.

He Hongjun put down the paper in his hand, slapped his thigh and said, "Oh! I will know why this plane can fly."

"Remember this time! This is Bernoulli's Law." Lin Xiyan said with a clear and smiling eyes at him.

"Remember, remember." He Hongjun laughed while blowing the paper, "This physics is quite interesting."
Chapter completed!