After He Hongjun finished writing this long string of words, he moved his fingers and raised his eyes to look at him and said, "What you said is too empty, I don't feel like a fart is useful, you tell me a little bit of image." ”

"More specific?" Lin Xiyan put down the fan in his hand and said, "Bernoulli's law, a very important law of physical force, which reveals the basic principle of aircraft take-off, was discovered by the famous father of fluid mechanics, Daniel Bernoulli in 1738, and its formula is like this. As he spoke, he pulled out the pen in his hand and wrote it down in his notebook, "This formula says that within the range of fluids, velocity is inversely proportional to pressure. This means that the faster the speed, the less stress. What is the concept of velocity? Velocity is ...... per unit of time."

"Wait...... Stop it. It knows me, I don't know it, and it's useless for you to write it down. I don't understand what I mean? It's more dizzy to me than what you just said. He Hongjun pointed to the notebook with his index finger and said, "Don't use technical terms, I don't understand them." You are a teacher who is not qualified, don't you know that it varies from person to person?"

"I can be regarded as having an understanding of what it means to be a rake of Zhu Bajie. Lin Xiyan looked at him with a smile and said, stroked his forehead and said, "In that case." He pulled the notebook directly to his side, "Fan! ”

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

Lin Xiyan put a few strokes on the notebook, "This is a cross-sectional drawing of the wing of the aircraft, its top is an arc, and the bottom is a straight line, which side is longer above and below!"

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

"That's right!" Lin Xiyan nodded and said further, "So when the air passes through the wings, the flow speed above will be faster than that below." Then there is a pressure difference between the top and the bottom. This pressure difference is called lift. It was through this lift that the plane took to the skies. Looking at He Hongjun, who was full of mosquito coils, he said, "Got it?"

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

Lin Xiyan pursed his lower lip and said, "I thought you had been to Kang Da anyway, but now it seems that you can't do anything other than reading, reading newspapers, and writing inspections." ”

"you. He Hongjun knocked him on the arm with a fan, "You just wrote the check! I don't have to write it now." ”

"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 case, and vertically split the manuscript paper in half from the middle.

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

"Needless to say, it must be jumped in both directions!" He Hongjun said immediately, his fingers gesturing and flying outward.

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

He Hongjun stood up and said, "Blow it, I'm sure I'm right." ”

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

"Oh my mother!" He Hongjun exclaimed, "how did it get caught together?" He continued to blow without believing in evil, and the result was the same, "It's amazing!"

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

"Hmm!" He Hongjun nodded.

"I haven't played before!" Lin Xiyan looked at him with a smile and said, "You continue to play." ”

"Uh......" He Hongjun said with a sneer, sitting down.

"Uncle, Uncle He, what are you playing?" Zhou Guangming asked, looking at them.

"The light came just in time, Uncle He will play a trick for you. He Hongjun looked at Zhou Guangming and smiled.

"Okay, yes! What a trick. Zhou Guangming looked at He Hongjun with interest and said.

He Hongjun blew between the two pieces of paper, "How is it?

"It's fun, it's fun, but why blow on them, how do they go to the middle, why don't they face both sides!" Zhou Guangming looked at He Hongjun with puzzled eyes and asked.

"This ...... That ......" He Hongjun was blind, and he didn't say a reason for a long time.

"Haha......" Lin Xiyan looked at the unlucky He Hongjun and smiled unkindly, "Yes!

"Don't laugh, hurry up and explain to your nephew. He Hongjun looked at him and urged.

"You can't use your own brains! What does this little experiment show?" Lin Xiyan looked at him and counted.

He Hongjun raised his eyes to look at Lin Xiyan, and then looked at the piece of paper in his hand, "The Bernoulli's law you just talked about, the faster the speed, the less pressure, I blow into the middle of the paper, and the air in the middle must flow fast!" ”

"Okay! Lin Xiyan gave him a thumbs up.

"That's right, I'm already smart!" He Hongjun said boastfully, "It's just that this brain hasn't been used for this in the past." ”

"It's really that you're fat, and you're gasping. Lin Xiyan looked at him and shook his head and smiled.

"I'm having fun. Zhou Guangming looked at He Hongjun and said.

He Hongjun handed him the piece of paper in his hand, and Zhou Guangming was having fun.

"That's the wonderful thing about Bernoulli's Law. Lin Xiyan looked at He Hongjun and continued, "Then if you change it to a piece of paper." I blow on top of this piece of paper, how will it move?" he said and looked at Zhou Guangming and said, "Give me a piece of paper." ”

"Oh!" Zhou Guangming handed one of the pieces of paper to Lin Xiyan, "Uncle." ”

He Hongjun scratched his chin and said, "Is that very simple? You blow on the paper, according to what you just said, the speed on the paper is high and the pressure is small." He gestured with both hands and said, "Will the paper float up?" excitedly looked at the paper in Lin Xiyan's hand, blew it with his mouth, and saw the paper floating, his eyes were straight.

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

He Hongjun blew hard and had a lot of fun.

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

He Hongjun put down the paper in his hand, patted his thigh and said, "Oh! If you say that, I know why this plane can fly." ”

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

"Remembered, remembered. He Hongjun blew the paper and laughed, "This physics is quite interesting." ”

"Uncle, is this physics?" Zhou Guangming's innocent eyes shone brightly.

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