The first class is physics class. Physics teacher Kuang Haihan is also the director of academic affairs. Unlike the full-time school leaders of municipal and provincial key middle schools, those who can serve as principals and political and educational directors in junior high schools in towns must have a good ability to teach in addition to some relationships in the education commission school district.

The physics class starts from the second grade of junior high school. The basic principles of mechanics are learned in the third grade of junior high school, and the electromagnetic principle is learned in the third grade of junior high school.

Qin An was very interested in physics classes in the third year of junior high school. He remembered that after learning the circuit, he began to disassemble every piece of electrical appliances, TVs, washing machines, radios, and even electricity meters and light bulbs in his home.

He felt that the main table of the dormitory building often tripped and the fuse was blown. After knowing the principle of the fuse, he replaced the fuse with iron wire, which caused a small fire. Although it did not cause any major losses, Qin Huai and Li Qin were apologizing to others for a whole week, and Qin An was beaten to death.

Qin An always felt that the knowledge learned in junior high school and high school is the real essence of quality education... as long as there is no exam.

With these basic circuit knowledge, Qin An can basically repair it in his future days, such as TVs, refrigerators, microwaves, etc., as long as the circuit board is not seriously damaged.

Kuang Haihan is a tall and thin middle-aged man, about the same age as his father Qin Huai. Although he was very wonderful, Qin An felt that there was no need to listen after turning a few pages briefly.

In a class, it usually only talks about a few pages.

Qin An took out a piece of white paper and pencil, wrote and painted on the paper.

Sun Sun glanced at him from time to time. At first, he thought Qin An was away again, but when he saw him marking angles, vector lines, coordinates, and writing a bunch of calculation formulas on it, Sun Sun suddenly realized that he was reviewing mechanics and physics in the second grade of junior high school.

After class, Qin An still did not stop writing, but he had more graphic structures on his original simple drawings, which no longer looked like a mechanics diagram.

"What did you draw? I drew a whole class." Although Sun Sun didn't like Qin An doing some weird things during class, he was a little curious after all.

"I want to make a slingshot, which is extremely powerful, and one hundred." Qin An lay on the table, looking attentive, as if he was doing something amazing.

Sun Sun patted his forehead. Qin An was no longer helpful. He actually thought he was reviewing mechanics and physics.

Although Qin An scared Tu Gang this morning, he did not think that he could scare him if he encountered Tu Gang again next time.

The biggest difference between an adult and a minor is not physical strength, but after an adult integrates into society, he always has some social strength, allowing him to deal with many crises and be more confident. When he feels danger, he cannot solve it independently by himself, he will be at a loss.

Minors are different. They can not solve many problems independently, and it is difficult to master social power for their use.

Although a gangster like Tu Gang is only fifteen years old, the auto repairmen in his auto repair shop are equivalent to social forces that can be used by him, which is also the real reason why other children are afraid of him.

Qin An changed from an adult to a minor, and there was always a sense of crisis that he lost the social power he was used to. For a thirteen-year-old child, carrying a dagger on his body would not have much effect, and sometimes it would bring greater danger to himself.

Qin An decided to make a slingshot. Most people only regard it as a toy for children, but real slingshot players know that it is not too difficult to have a powerful composite slingshot and use eight-stitch hose as power. After a little practice, it is not too difficult to hit an object with a 1-centimeter diameter of 10 cm diameter with a steel ball fifty meters away.

A little closer, a marble shot from a composite slingshot can completely penetrate the palm of an adult's hand.

The slingshot has great damage, but as long as it does not hit fragile parts such as the eyes, the possibility of malfunction and death is very small, and it can also maintain deterrence. This is also the reason why Qin An chose to make a slingshot to defend himself.

After Qin An drew out the structural diagram of the composite slingshot, he realized that with his current ability, it was too difficult to make a composite slingshot. Even if it was barely made, it would be difficult to exert the stability and accuracy of the composite slingshot.

It seems that only ordinary slingshots can be made. The materials are properly selected and the rubber bands have sufficient toughness and great power, but the accuracy and stability are much worse than that of a large part of the composite slingshot.

Qin An is also a veteran in playing slingshots. As long as he is familiar with slingshots and practices more, his accuracy and stability can be compensated by his proficiency.

After lunch, Qin An ran out of the school. There was an old man named Liu in the back mountain of the school. This old man had no children and was alone. Until more than ten years later, Old Man Liu suddenly became rich. It is said that his wealth reached seven figures and he married a yellow girl as his wife.

The reason why Old Man Liu got rich was the yellow rosewood in his yard and a table of eight immortals in the Huanghuali.

In Qin An's memory, the price of huanghuali wood that can be used as furniture for adults exceeds 6 ooo yuan per kilogram, and some special huanghuali wood boards are even more than 20,000 yuan per kilogram, reaching 20 million a ton.

After the price of Huanghuali wood was frying, Old Man Liu suddenly got out, and Qingshan Town became lively. Some people's ancestral house beams were climbed onto the roof by thieves to untied the tiles and saw them away. Some people's ancestral graves were dug up, and the Huanghuali wood coffin was stolen. The craziest thing was a clerk from the town government office saw a section of Huanghuali wood staircase handrail in the government office building.

Qin An ran to Old Man Liu's house, of course he was not stealing Old Man Liu's Eight Immortals Table, he just wanted a tree branch.

"Grandpa Liu, I want to pick a branch from your tree." Qin An asked openly when he saw Old Man Liu sitting in the yard with bamboo baskets.

"What are you doing to pick that thing?" Old Man Liu raised his head. He didn't know Qin An, but he could also guess that Qin An was a junior high school student in a nearby town.

"Make a slingshot." Qin An smiled.

"You guys nowadays just don't study hard... You pick this old tree for a while, and the wood is hard enough, and it's also suitable to make a slingshot." Old Man Liu said casually, this is not a big deal.

Qin An picked up Old Man Liu's saw and climbed onto the Huanghuali tree with a diameter of nearly half a meter.

Huanghuali trees are easy to plant and easy to live, but they are extremely difficult to grow into a vegetarian tree. It takes nearly a thousand years to grow to thirty centimeters. Qin'an can't guess how old this Huanghuali is.

Qin An chose a tree branch that is most suitable for making slingshots, sawed it down, and polished it with Old Man Liu's tools.

Qin An was so happy in his heart. What is the compound slingshot? This is the best. It is not an exaggeration to say that it is a work of art.
Chapter completed!