1. Fun children's encyclopedia knowledge
1, why the more you use your brain, the more flexible it is?
Because in the process of using the brain, the blood supply to the cerebral vessels is sufficient, and they are often in a stretched state, which makes the brain more developed and avoids brain aging.
2. Why are you talking in your dream?
When people sleep, the brain begins to rest, but due to lack of sleep, the nerve part responsible for language is in an excited state, and people will talk in their sleep.
3. Why do some people have black skin and some people have white skin?
Skin color is related to people's race and sunlight exposure. People who often bask in the sun or work outdoors have darker skin.
4. Why do nails grow back after being cut off?
Nails are made of keratin, so as long as new keratin is produced, nails will be pushed outward. Therefore, nails will always grow.
5. Why do people get old?
The human body is made up of cells, and 125 trillion cells are dying every second. People's nerve cells have no regenerative ability and die of aging, so people will get old.
2. Fun children's encyclopedia knowledge
1. Why is noise a health killer?
Because noise often makes people upset, causing headache, dizziness, fatigue, insomnia and memory loss. It even makes people's blood pressure rise and their heartbeat change. After a long time, people will get diseases such as heart disease, high blood pressure and gastric ulcer. The child's body is not yet mature, which will lead to the loss of normal hearing and mental development of the ear.
2. Why is porridge good for breakfast?
After a night of peristalsis, people's stomachs are basically empty of food. Get up in the morning and your stomach is empty. At this time, if you eat some cold and hard food, it will undoubtedly stimulate the stomach and increase the burden on the stomach. Drinking porridge will stimulate appetite, strengthen the spleen and be economical.
3. Why is it not good to read in strong light?
Read in the sun (sunlight, electric lights, etc.). ) It will irritate the eyes and make them tired and dizzy quickly. It will hurt your eyes after a long time. Therefore, don't read books or newspapers under strong light.
4. Why is the air outlet not good?
Because when people sleep, sweat pores are all open, and when they sleep at the tuyere, their skin will contract when they catch cold, which will close their hair and block the heat in the body. When the sweat is collected, people will easily get sick, and even make their faces paralyzed, resulting in the problems of squint and crooked mouth (facial paralysis).
5. Why do you have a good appetite after exercise?
During exercise, due to the deepening of breathing, the diaphragm moves up and down greatly, and the abdominal muscles move back and forth, so that the gastrointestinal tract can be massaged and helpful for digestion; In the process of exercise, the consumption of the body increases and the metabolism accelerates, which requires the digestive organs to strengthen their work and better absorb nutrients from food to meet the needs of the human body. So after exercise, of course, the appetite is good.
6. Why is there static electricity?
Static electricity does not refer to static electricity, but refers to static electricity formed when charges accumulate on objects or surfaces. When an electrostatic object contacts an object with zero potential (grounded object) or an object with potential difference, charge transfer will occur, which is the phenomenon of spark discharge we see every day. For example, dry weather in winter, messy hair combing, tingling of electric shock when touching others or metal conductors, crackling sound when undressing at night, flashing lights, etc. are all phenomena of human body with static electricity.
3. Fun children's encyclopedia knowledge
1. Why are the mouths of cattle and sheep still moving when they are not eating grass?
Cattle and sheep swallow food quickly every time they eat, and then store it in their stomachs. But there are no digestive glands in their stomachs, so they can't secrete digestive juice. Fermented food will be sent to the clean stomach and then sent back to their mouths bit by bit for chewing. This is why the mouths of cattle and sheep are still moving when they are not eating grass.
2. Why do zebras have black and white stripes?
The black and white stripes of zebras are their protective colors. Zebras live on the African savannah. They have many natural enemies, such as lions and leopards. These black and white stripes can hide themselves from the enemy.
3. What's the use of an elephant's long nose?
The elephant's long nose can not only breathe and smell, but also absorb water and spray it on the body for bathing. It can also pull up the grass on the ground, roll it up and send it to the mouth. When walking, the elephant uses its long nose as a crutch to explore the road ahead. When in danger, the elephant uses its long nose as a weapon to roll up the enemy and throw it out.
4. What's the difference between a giant panda and a red panda?
Giant panda and red panda are two different animals. Giant pandas are slow and gentle. Its hair is black and white, and its tail is short. Red pandas are very flexible and can climb high branches. Its hair is reddish brown, its tail is thick and long, and there are rings on it.
5. Is the pig really stupid?
Pigs are not stupid. Their sense of smell is very sensitive and can help people find lost things. There are also some piglets trained to perform dances, acrobatics and other programs.
4. Fun children's encyclopedia knowledge
1. Why are fireworks colorful?
Fireworks are filled with various drugs, some of which are specially responsible for burning, and some can emit strong light. The color of fireworks is due to the chromogenic agent. Chromophores are actually some common metal compounds, which burn when heated, making fireworks show various colors.
2. Why can balloons fly into the sky?
Balloons are filled with hydrogen or helium, which is much lighter than air.
3. Why can a mirror "deform" people?
Ha ha mirror is made of uneven glass, some places are concave, some places are convex, and some places are distorted, which makes the characters in the ha ha mirror change greatly.
4. Why can an eraser erase pencil words?
The main component of rubber is generally natural rubber. We can erase the graphite powder left on the paper with some paper fibers so that we can write on the paper again.
5. Why do you wear cotton-padded clothes to keep warm?
The cotton coat is filled with cotton, and there are countless holes in the fluffy cotton fiber, with a lot of air hidden in the middle. Air is an excellent heat insulator, which prevents the heat emitted by the human body from going outside, thus keeping the body warm.
5. Fun children's encyclopedia knowledge
1. Why do chickens eat sand?
Answer: The chicken's food is mainly rice and wheat, but it has no teeth and can't chew these foods, so they need sand to help grind the food. In addition, the chicken's stomach can store sand and stones, which is the way it uses sand to help digest food.
2. Why don't homing pigeons get lost?
Answer: The pigeon has good eyesight and memory. There is a magnet on its head, which can guide it. In addition, it can adjust the flight direction according to the positions of the sun, stars and moon. With this special skill, homing pigeons can complete the task of delivering letters.
3. Why do dogs stick out their tongues in summer?
Answer: In order to dissipate heat. Dog sweat glands grow on the tongue, so when the weather is hot, in order to dissipate heat, the dog will stick out its tongue to let sweat out and take away the heat.
4. What's the difference between a kitten's beard?
Answer: A kitten's beard is a very standard ruler. The mouse escaped into the mouse hole and measured it with its beard to know whether it could go in or chase it. If the beard touches the hole wall, it means that the hole is too small to get in. If the beard doesn't touch the hole wall, it means it can go in.
5. Why can police dogs help solve crimes?
The olfactory cells on dogs' noses are particularly developed, and the mucous membrane covering them can secrete mucus to help them distinguish different smells, so their noses are particularly sensitive.
Specially trained police dogs, as long as they smell the smell left by the bad guys, can firmly remember it, and then find the target according to this smell, so as to catch the bad guys and solve the case.