Like Meng Chencheng, he likes to quarrel with others, especially with his fourth brother. The two of them can use the skills of quarrels to divide the work and cooperate. I don’t know how many things can be accomplished. Meng Chenjun, in order to learn from his father’s business and factory, he does not establish the concept of protecting the earth’s ecology from a young age. An entrepreneur must have an ecological concept to benefit society rather than pollute the environment.

I hope that Ning Yunxi’s efforts to the children can all keep in mind.

Thinking of his own question, Meng Chenxi took a breath and said frankly: "Sister-in-law, I can't think of it. It was Cao Ximin who helped me think about it."

Ning Yunxi nodded slightly to the third child, thinking that once the big boy breaks through his current state, he will spread his wings and fly high.

Meng Chenxi took out the two small balls and wooden boards that he had prepared and demonstrated them according to the steps Cao Ximin taught her.

Dong,—— Dong.

Leilei listened to the sound of the third aunt's two small balls, and shouted with his little mouth: "Dong, dong."

"What is this?" Ning Yunxi asked his son.

"Echo-" Leilei answered according to what his third aunt said.

Ning Yunxi smiled and imitated his son: "Did you understand the principle that your third aunt demonstrated to you?"

Leilei didn't dare to pretend to be garlic in front of his amazing mother. He squatted his little butt into his mother's arms and lowered his little head shyly. In fact, he really didn't understand it.

It is definitely impossible for such a young child to fully understand the principle of echo. This involves what sound source is, what is the speed of sound propagation in various media, the reflection of sound waves, etc. These things can only be explained in primary school natural science or junior high school physics classes. This kid has not been in kindergarten. However, the third brother is already qualified to be able to see the two small balls demonstrating echoes simply and intuitively.

Meng Chenxi was already thinking about how his sister-in-law asked her to interpret the echo. By the way, what she wanted to be an announcer, and the announcer relies on sound to spread the information she wants to express, but it is not that the announcer only has the voice to use. In order to let the information be transmitted to more people, whether it is sometimes very tense not only depends on sound.

Do more social practice and get close to various groups. This is my sister-in-law’s advice to her how to take a career path in the future.

Next, it was the two brothers' turn to have a question. Only then did the other children realize that the questions of the two brothers were actually the same, and please explain the theoretical basis for how to make an iron rod into a needle and grind it into a needle.

The two brothers seemed to have run errands to check information for this question, and their faces did not look very relaxed, especially when they thought that Ning Yunxi's questions were not only aimed at three-year-old Leilei who had deep meaning to them.

"The iron rod is ground into a needle, and does not discuss methods such as plastic processing and crushing and re-grinding. It only considers the mass loss caused by friction. This is obviously a simple wear problem. The time required is equal to the total wear amount divided by the wear speed. The total wear amount is very good, basically equal to the mass of the iron rod. The key is to determine the wear speed. According to the Archard wear formula, when materials slide together, the volume loss caused by wear is-"

The top students talked about science formulas and other things, the third, fourth, fifth and child Leilei, all of whom were very big, and they felt very far away from their two brothers.
Chapter completed!