Li Er didn't seem to be very interested in mathematics, so he hastily flipped through a few mathematics books, put them back on the bookshelf, and prepared to go up to the fifth floor to have a look. Pen ~ fun ~ pavilion www.biquge.info

Wang Mai's eyes rolled, and he stopped in front of Li Er: "Your Highness, do you know how to make the ballista exert its maximum power on the battlefield?" ”

Li Er thought for a while: "Isn't it with black powder?" "The ballistae in Luoyang were brought to Wugao Pass to show their might, and the Xia army was in chaos, and the great victory of the Tang army was inseparable from the contribution of ballistas and black powder.

"With black powder, it is naturally infinitely powerful, but this is related to the power of black powder itself, where does His Highness think the benefits of ballista are?" Wang Mai asked.

"Wang Fugui mentioned it to this king, and he said that the ballista is simple to operate, has a long range, and has a high shooting accuracy......," Li Er said while recalling the advantages of the ballista.

Wang Mai took out a book on the shelf, turned a few pages, pointed to the parabola on it and said: "There is still a lot of room for improvement in the accuracy of ballista shooting, and the secret is in this book." ”

"Oh?" Li Er was interested now, but after reading it for a long time, these book-like symbols gave him a headache, and he shook his head: "Let's ask Mr. Wang to explain the truth for this king." ”

It seems that Li Er is a partial student in terms of learning, obviously a liberal arts, Wang Mai's psychology is finally much more balanced now, pointing and slowly explaining the principle of throwing objects for him: "...... How far a shell can fly can be calculated by determining the initial velocity of the shell and the angle of elevation, and then excluding the drag of the air, so that the landing point of the shell can be accurately estimated. ”

Although Wang Mai had tried his best to simplify the mathematical knowledge inside, Li Er was still confused after hearing it, and his eyes were clouded: "This ...... What is the resistance of air? ”

Wang Mai glanced at Ma Zhou encouragingly, Ma Zhou nodded, and stretched out a hand: "Please Your Highness move downstairs, there is a very simple experiment that can prove the existence of qi resistance." ”

A group of people went downstairs in a mighty way, Ma Zhou followed behind, holding a silk cloth, the scholars in line downstairs took a look, and knew what this was for, this experiment had been done many times before, and it would be staged in the pulpit under the book every once in a while.

Ma Zhou came to Li Er with the silk cloth in his hand: "This silk cloth is very light, and it can be moved by the next person, but I only need to make a small movement, even if it is a strong man, I don't want to make it move a little." ”

Li Er smiled and shook his head, obviously not convinced.

Ma Zhou didn't argue, he took the end of the cloth and threw it out, and the cloth was unfolded, and after inserting a hardwood on each side of the silk cloth, Ma Zhou turned around and saluted Li Er: "I dare to borrow the personal guards around His Highness, let them give it a try." ”

Li Er nodded, and the two guards with big shoulders and round waists next to him stepped forward, their faces full of dissatisfaction, just a small piece of cloth, even this thin scholar can pick it up, can he still stump himself?

"Look at this person, I'm going to make a joke for a while." The onlookers in the crowd whispered.

"They won't believe it until they see it."

"yes, didn't we think so at the beginning?"

Ma Zhou said a few words to the two guards, the two of them nodded, and one of them stood up easily on the side of the unfolded silk cloth.

Only then did Li Er realize that this silk cloth was big and wide, and as soon as the two of them erected the whole cloth, which side of the windward side quickly swelled.

The two guards barely smoothed the silk cloth with their strength, and wanted to move forward, but they felt that the wooden pole they were holding in their hands was as heavy as ten thousand pounds, and no matter how hard they tried, it was difficult to move a little, and they were so red that their faces were red.

Ma Zhou smiled very happily, he was very unconvinced at the beginning, but he was educated by Wang Mai, and now it is the turn of others to suffer this hardship, and he is a little gloating in his heart. This cloth is not an ordinary silk cloth, it is deliberately thickened, it is not permeable to the wind at all, the direction facing the two is just a tuyere, and now it is the time of the change of seasons, the wind is strong, and it is tantamount to a fool's dream to carry such a big resistance to go forward.

"Ahh Li Er's two personal guards struggled to support, let alone go forward like this, I am afraid that they will have to retreat, the two glanced at each other, shouted, and worked together to try to save some face.

A tearing sound came from the "hiss......" The two of them used too much force, and they actually pulled the place where the wooden pole and the silk cloth were connected alive.

"That's it!" Seeing this, Li Er stopped the two of them, "Come back." ”

The two put down the silk cloth in frustration and knelt down in front of Li Er: "King, my subordinates are incompetent......

Li Er shook his head: "I don't blame you, it's these two people who are too cunning and use the power of the wind." He looked at it for a long time, and he had already seen the doorway, this thing and the sail are the same thing, and it is not something that one or two people can move at all.

"Your Highness," Ma Zhou arched his hand towards Li Er, "the wind is not caused by the wind, the wind is formed because of the flow of air, so the wind is also a type of air resistance. ”

"Oh?" This statement is the first time Li Er has heard of it, although he has to make offerings to Feng Bo every year during the sacrifice, but he doesn't really believe in such a thing as gods and monsters in his heart, and now he is interested in hearing Ma Zhou's explanation.

"Although qi cannot be seen or touched, it can prove its existence." Ma Zhou arched his hand towards Li Er, and quickly ran to the building, holding a cup full of water in his hand when he came out again. "Your Highness, please look!" Ma Zhou took out the piece of cardboard he had prepared earlier from his arms and buckled it on the cup, and then quickly turned the cup upside down.

Li Er was stunned and looked at the cup that didn't spill a drop of water: "This ......"

Ma Zhou raised the upside-down cup in front of Li Er, Li Er took it carefully, looked at it curiously for a long time and didn't understand what was going on, and flicked the piece of paper on the mouth of the cup with his hand, and with a "bang", the pouring water suddenly poured him a shoe.

"Your Royal Highness......" Ma Zhou looked at Li Er a little nervously, he didn't expect Li Er to be so curious, which was a bit self-defeating.

The guard next to him hurriedly leaned down and wiped Li Er's shoes clean with his sleeves, Li Er waved his hand and asked the two to retreat, not caring about this surprise, but looking at Ma Zhou, waiting for him to explain the truth.

"Or because of the gas, it's holding the piece of paper to prevent the water from flowing out of the cup." Seeing that Li Er didn't blame him, Ma Zhou immediately breathed a sigh of relief and explained the principle.

"I see," Li Er nodded as if he didn't understand, "This invisible and untouchable qi has such great power?" It's a university question. ”

Ma Zhou smiled: "Your Highness, although this qi cannot be seen or touched, there is a way to weigh it." ”

"What?" Not only Li Er, but even the officials he brought with him were all exclaimed.