One Piece of Song Dynasty

Arriving at the door of Fujian Communication University, Li Qingling and others stomped their feet while waiting for Tang Wan to appear. Tang Wan came out with red sleeves soon after class. Seeing Tang Wan come out, Li Qingling stepped forward and held Tang Wan's hand and said: " Wan'er, your hands are so cold. Why didn't you bring out the gloves I bought for you?"

Tang Wan pouted and said, "I came out in a hurry and forgot to bring it with me. I'm not afraid you'll have to wait too long."

Li Yixuan, who was standing nearby, interjected: "Second brother, it's okay. I didn't expect my second sister-in-law to be so beautiful."

Li Qingling quickly introduced: "Wan'er, this is my third brother Li Yixuan, who is currently studying at Fujian University of Science and Technology."

Tang Wan saluted and said, "Hello, Mr. Li."

Li Yixuan hurriedly returned the gift: "Second sister-in-law, there is no need to be polite. Please come quickly. My second brother and I have played together since we were young. We still have a very good relationship."

Li Qingling said: "Okay, let's go, let's go to Tianxiang Tower for dinner. There is a coal stove in Tianxiang Tower, so it's warm."

When we arrived at Tianxiang Tower, we ordered some common dishes. After a few people sat down, Li Qingling said, "Wan'er, how are you preparing for the final exam? There will be an exam the day after tomorrow."

Tang Wan took a sip of hot tea and said, "It's okay to pass the exam, but it's hard to say how well you can pass the exam. How about you two brothers?"

Li Qingling replied: "I'm about the same. I can definitely pass the exam. I don't know how well I can do, but my third brother is a top student. His grades are much better than mine. He is ranked first in their major." Several former."

Li Yixuan said with a sneer: "Second brother, you deserve the reward."

Tang Wan was surprised and said: "So powerful, what kind of profession is Yixuan?"

Li Yixuan scratched his head and said, "I am a physics major at Fujian University of Science and Technology."

Tang Wan wondered: "Physics"

Li Qingling explained: "This is a major currently only available at the University of Science and Technology."

Li Yixuan said: "I heard that the upcoming Shipbuilding University, Ocean University, National University of Defense Technology, and Engineering University will all have physics majors or physics-related majors."

Logan asked: "What is physics mainly used for?"

When talking about his major, Li Yixuan said seriously: "The physics we currently study mainly studies mechanics, electricity, optics, heat, aerodynamics, and acoustics. In the future, it may be subdivided into more disciplines. "

Tang Wan frowned and said, "It sounds so complicated. Then what's the use of studying physics?"

Li Yixuan smiled and said: "Haha, it's a bit complicated. Physics is of great use. My second sister-in-law has been on a boat before. Today's big ships rely on wind power. If physics is good, we can improve the ships so that they can be used better. The power of the wind, of course, is more than that. For example, why does this small iron ball fall to the ground when I let go of my hand, instead of flying into the sky or floating in the air."

Tang Wan said: "Isn't it common sense that an iron ball player falls to the ground when it is loose? Is there any knowledge here?"

Li Yixuan nodded and said: "Of course, there is a lot of knowledge here. Don't think it is common sense in the eyes of ordinary people. In fact, a lot of common sense in our eyes has a lot of knowledge. It's just that we don't usually explore it. Once we explore it, it will I discovered many interesting phenomena, like the iron ball I just mentioned. The reason why the iron ball only falls on the ground is because of the existence of gravity. We live on a big ball. This ball we call the earth. The earth exists. Gravity, gravity attracts us tightly to the ground. If there was no gravity, we might be floating in the air."

Tang Wan was surprised and said: "The place we live in is a round ball, isn't it flat ground?"

Li Yixuan nodded and said: "Yes, it is easy to verify this. Just go to the beach and you will understand. When a ship comes from a distance, the first thing we see is the mast and then the hull. If we survive If the place is flat, then you should see the entire hull, not just the mast."

Tang Wan nodded and said: "Well, when I have time, I will go to the beach to have a look. Then what is the use of studying gravity?"

Li Yixuan said: "Of course it will work. If gravity is studied, flying in the future will no longer be a dream, it will be achievable."

Tang Wan was shocked and said: "Flying sky is really not possible because of the existence of gravity."

Li Yixuan smiled and said: "Of course it is true. Gravity also has its own size. When the force you use exceeds gravity, you can go up to the sky. Otherwise, why would birds be able to fly in the sky all day long? In fact, we can make it now A device that makes people fly.”

Tang Wan asked: "What is a device that can make people fly into the sky? Why not make it?"

Li Yixuan replied: "The flying device we can make now is called a hot air balloon. To put it simply, the buoyancy generated by heating the air in the sphere with fire takes people up to the sky. Of course, it also involves density issues. I won’t go into details. At present, There is no problem with flying hot air balloons, but we don’t yet have people who are proficient in controlling the flight and landing of hot air balloons. You must know that if you accidentally fall down from the sky, you will die. Of course, we have also selected a few people to train and control hot air balloons. Wait until you can control a hot air balloon before flying high into the sky."

Tang Wan hurriedly asked: "When you become more proficient, can you take me to heaven? I also want to go to heaven to see it."

Li Yixuan glanced at Li Qingling and said: "Second sister-in-law, you have to ask my second brother about this and he agrees."

Tang Wan blinked her beautiful eyes and looked at Li Qingling and said coquettishly: "Qingling"

Tang Wan's cooing voice made Li Qingling feel a little scared: "Okay, okay, as long as there are no problems with Third Brother, I will accompany you to heaven."

Li Yixuan smiled and said: "I'm sure it's fine. Then when you return to school in the next year, you can wait for my letter. In fact, hot air balloons are not real aircraft. The real aircraft is called an airplane."

Tang Wan wondered: "What is this airplane?"

Li Yixuan said: "Airplanes look very similar to birds, but we can't make airplanes with our technical conditions now. Second sister-in-law, if you really want to understand the role of physics, you can go to Xinghan Road. There are Many physical representations, such as trains and thermal power plants.”

Tang Wan nodded and said: "Well, okay, I will definitely go if I have the chance. I am still very interested in Xinghan Road."

Li Qingling interrupted: "Okay, stop talking. When it comes to physics, my third brother can talk to you non-stop all day long. Wan'er, let's go back to the north together after the exam."

Tang Wan smoothed his hair and said, "Okay, you go back to Yanjing, and I'll go back to Zhengzhou. We just happen to be together."

Li Qingling nodded and said, "Then we've decided that we'll pick you up from your school after the exam."

Logan said: "Yeah, okay."

So five days later, after finishing the exam, Tang Wan, Li Qingling, Li Yixuan and others embarked on a journey back north.