Life common sense science 1.50 small scientific knowledge
1. Rabbits beat the ground with their legs to transmit information, mostly with their hind legs, which is a way for them to express their feelings to female rabbits. 2. The biggest monkey in the world is a baboon and the smallest monkey is a bonobo. 3. The real name of "Four Elephants" is Elk, which is a rare animal in China. 4. Why does sorbet get angry? The reason why sorbet bubbles is because there is a lot of invisible water vapor in the outside air. When it comes to cold sorbet, it will liquefy into droplets when it is cold. It seems that the sorbet is bubbling.
5. Why do sunflowers always face the sun? Sunflower stems contain a wonderful auxin. This auxin is very afraid of light.
When it is illuminated, it will go to the backlight side, and the cells on the backlight side will multiply rapidly. Therefore, the backlit side will grow faster than the bright side, which will bend the sunflower to light. 6. Why do cicadas shed their skin? Cicada's shell (exoskeleton) is hard and can't expand with the growth of cicada. When the cicada grows to a certain stage, the cicada's exoskeleton restricts its growth, and the cicada loses its original exoskeleton, which is cicada slough.
7. How do bees make honey? First, the bees spit the sweet juice of the flowers they picked into an empty hive. At night, they suck sweet juice into their honey stomachs to make it, and then spit it out and swallow it. It takes 100~240 times to make sweet honey. 8. Why do the stars twinkle? We see the stars shining, not because the luminosity of the stars has changed, but because of the occlusion of the atmosphere.
The atmosphere is between us and the stars. When starlight passes through the atmosphere, it will be affected by the density and thickness of the atmosphere. The atmosphere is not absolutely transparent, and its transparency will change according to its density.
So when we look at the stars through it on the ground, we will see that the stars seem to be flashing. 9. Why do people yawn? When we feel tired, a lot of carbon dioxide has been produced in our bodies.
When there is too much carbon dioxide, oxygen must be supplemented to balance the needs of the body. Because these residual carbon dioxide will affect our body's functional activities, then the body will send out a protective reaction, so we yawn.
Yawning is a deep breathing action, which will let us breathe in more oxygen and expel more carbon dioxide than usual, and it can also eliminate fatigue. 10, why can a snake walk without feet? Snakes have many scales, which are the outermost armor on their bodies.
Scales are not only used to protect the body, but also to be their "feet". When a snake crawls forward, its body will be S-shaped.
Every scale outside the S-shape will tilt upward to help the snake catch the uneven road when it moves forward. These scales cooperate with the muscles of the snake and can push the body forward, so the snake can walk without feet! 1 1. Why does hair turn white when people get old? There is a substance called melanin in our hair. The more melanin, the darker our hair will be.
Without melanin, hair will turn yellow or white. When human beings reach old age, various functions of the body will gradually decline, and the formation of pigments will be less and less, so the hair will gradually turn white! 12. Why do fireflies glow? Fireflies emit light because there is a luminous body at the end of their abdomen, which is filled with a lot of phosphorus-containing luminescent substances and luminescent enzymes, so that fireflies can emit flashing light.
The purpose of fireflies is not only lighting, but also courtship, vigilance and trapping. This is also a communication tool for them. Different kinds of fireflies emit light in different ways, frequencies and colors, so they can convey different information.
13. Why do you growl when you are hungry? When you are hungry, you will purr. This is because the food you have eaten before has almost been digested. Although the stomach is empty, the gastric juice in the stomach will continue to secrete. At this time, the contraction of the stomach will gradually expand, and the liquid and gas inside will be stirred up and purr.
Don't be embarrassed by your stomach growling next time! Because this is a normal physiological action. 14. Why can't ostriches fly? A giant ostrich, but they can't fly into the sky! This is not because their wings are useless, but because their feathers are too soft and their wings are too small to fly at all.
In addition, the ostrich's muscles are underdeveloped and its sternum is flat, which is not conducive to flying. Ostriches live in Africa. Because they have lived in desert areas for a long time, their bodies gradually evolved into what they are now in order to adapt to the environment.
15. Why can't the food in cans go bad easily? Lunch meat, black bean shad, tomato sauce beans.
They are all delicious canned food, which can be preserved for a long time without deterioration. This is because the can is sealed, so bacteria can't enter.
When people make canned food, they pump all the air out of the canned food and then seal it. In the absence of air, even if the food inside is contaminated with a little bacteria, they can't survive or reproduce! 16. Why does the baby cry all the time when it is born? Babies cry when they are born, not because they are unhappy, but because they are taking the first breath of air! When babies leave their mother's body and are born, the first breath of air will rush to their throats, violently impact the vocal cords, make them vibrate, and then make a sound similar to crying.
17. Why do lizards keep bouncing backwards when their tails are broken? In order to protect themselves, many lizards also protect their eyes and ears; When some lizards are attacked, their tails will be broken due to the severe contraction of their muscles. Because there are still some nerves alive in the broken tail, it will keep bouncing, thus distracting the enemy and running away.
Don't think that their lives will end like this. In fact, it only takes a few months, and their tails will grow back and move on. 18. Why is the squirrel's tail so big? Don't look at the relaxed mouse tail! When the squirrel jumps around the tree, its tail plays a great role.
It can keep balance when the squirrel jumps to the tree to avoid falling and being injured. In addition, this big tail can play a more protective role in winter, tightly surrounding the squirrel's body, which is convenient and practical.
19, why can't a human thumb have one or three knots? The average person has five fingers, the length of which.
2. What are the scientific phenomena in life to explain the observed phenomena in life with the learned scientific knowledge or
Things will fall-gravity; Day and night alternate-the earth rotates; The formation of the four seasons-the revolution of the earth; Rainbow appear-refraction of light; Specular reflection-reflection of light; Boiling water-boiling water; Water freezes-water freezes ... a lot. First, the clothing color is "white in winter and black in summer". This is the experience that people have summed up from their life practice. Do you know the scientific truth it contains? The natural environment we live in is colorful and beautiful, with red flowers, green grass, blue sky and white clouds ... all kinds of objects have their own colors. However, these gorgeous colors disappeared in the dark night. This shows that objects will only show color under the illumination of sunlight (white light). So why do all kinds of objects have colors under the same light source? As we all know, sunlight is a mixture of red, orange, yellow, green, blue, indigo and purple. Different objects have different absorption and reflection abilities for different colors of light. People can't see the light absorbed by objects, only the reflected light. So, in our opinion, what color light an object can reflect, it has. White things can reflect all colors of light, so they look white; But black things can absorb all colors of light, and there is no light reflected back, so they look black. The sun not only brings people light, but also brings a lot of radiant heat. For radiant heat, black only absorbs and does not reflect, while white is just the opposite. Generally speaking, dark things absorb more sunlight and radiant heat and reflect less. Light-colored things reflect more and absorb less. Therefore, people like to wear light-colored clothes in summer, such as white, gray, light blue and light yellow, which can reflect a lot of light and radiant heat and make people feel cool. It is best to wear black and dark blue clothes in winter. They can absorb a lot of light and radiant heat, and people naturally feel warm. When people understand the laws of nature, they can use them in production technology. For example, the surfaces of large open-air gas tanks and oil tanks are painted silvery white to improve their ability to reflect sunlight and radiate heat, so that the temperature of the tanks will not rise too high, so as not to cause explosion accidents. People also use the principles of reverse and absorption to conquer nature. Let it serve mankind. There is a Qilian Mountain in the northwest of China, which is covered with thick snow and ice. However, because the mountains are very high and the weather is very cold, even in hot summer, strong sunlight and radiant heat are reflected back by dazzling white snow and ice, so the snow can't melt. As a result, a large area of land under the mountain was barren due to lack of water. After liberation, the party led the people to March into nature in order to make Qilian Mountain pay water. The plane scattered carbon black on the snow in Qilian Mountain, and the black carbon black absorbed light and heat desperately, so that the snow with carbon black melted, and finally there was a torrent of snow water in Qilian Mountain. Second, raw eggs and cooked eggs are two identical eggs, one raw egg and one cooked egg. How to distinguish them without destroying them? After placing two eggs on a relatively smooth table, rotate the eggs at the same time with roughly the same force. Raw eggs and cooked eggs stop first. We learned this method on TV in primary school. So what is the principle? The difference between raw eggs and cooked eggs is that the contents of eggs are liquid and solid respectively. When the eggshell is forced to rotate, due to inertia, the eggshell begins to rotate, while the liquid contents remain static, so there is a certain friction resistance between them, and there is also friction resistance between the eggshell and the desktop, so the rotation stops soon. When the eggshell is forced to rotate, the eggshell and the contents rotate together without relative movement. Only by overcoming the small friction on the desktop can it rotate for a long time. Third, the magical magnetized water magnetized water is a kind of water magnetized by a magnetic field. Let ordinary water pass through a magnetic field with a certain intensity at a certain speed along the direction parallel to the magnetic induction line, and ordinary water will become magnetized water. Magnetized water has various magical effects and is widely used in industry, agriculture, medicine and other fields. In industry, people initially only used magnetic fields to treat a small amount of boiler water. In order to reduce scale, magnetized water is widely used in the cooling system of various high-temperature furnaces, which plays an important role in improving cooling efficiency and prolonging furnace life. Many chemical plants use magnetized water to accelerate chemical reaction and increase output. The strength of concrete is greatly improved by mixing concrete with magnetized water in construction industry. Textile mills desize with magnetized water, and dyeing mills use magnetized water for coloring, which has achieved good economic benefits. In agriculture, soaking seeds in magnetized water to raise seedlings can make seeds grow. Irrigation with magnetized water can loosen the soil, accelerate the decomposition of organic fertilizer and promote the growth of crops. Through practice, it was found that the yield of soybean, corn and vegetables such as radish and cucumber increased by 10~45%, and that of rice, wheat and rape increased by 1 1 ~ 65438+. Can reduce livestock diseases and gain weight quickly. In medicine, magnetized water can not only kill many kinds of bacteria and viruses, but also treat many diseases. For example, magnetized water is effective in treating various lithiasis (gallstones, bladder stones, kidney calculi, etc.). ), stomach trouble, hypertension, diabetes, cold. For people who are not sick, drinking magnetized water often can also play a role in disease prevention and fitness. In daily life, magnetized washing powder solution is used to wash clothes. This is an unsolved mystery. Some scientists think that water molecules themselves are small magnets. Because the opposite magnetic poles attract each other, many water molecules in ordinary water will attract each other first, forming a huge "molecular group". This "molecular cluster" will weaken many physical and chemical properties of water. Ordinary water will break through the original "molecular cluster" and become a single high-energy water molecule under the action of magnetic field. of course，
3. Life science tips
1. If you eat spicy food and think it will kill you, just put a little salt in your mouth, hold it, spit it out and rinse your mouth, so it won't be spicy; ? 2. Yellow teeth, you can chew peanuts in your mouth and brush your teeth for three minutes, which is very effective; 3. If there is a small area of skin damage or burns, immediately apply a little toothpaste to stop bleeding and relieve pain; ? 4. Always leave ugly tea stains in the cup filled with tea, and wash it with toothpaste, which is very clean; ? 5. Open your mouth slightly when you look up at the eye drops, so that your eyes will not blink; ? 6. If there is an ulcer in the mouth, stick it on the ulcer with vitamin C, and it will basically be fine after the ulcer dissolves; ? 7. Small dust enters your eyes, close your eyes and cough a few times, and the dust will come out by itself; ? 8. After washing your face, gently apply some fine salt on both sides of your nose with your fingers, and then rinse with water, so that blackheads and acne will be removed and pores will become smaller; ? 9. When you have just been bitten by a mosquito, it doesn't itch when you apply soap; ? 10. If the throat and gums are inflamed, cut the watermelon into small pieces at night and eat with salt. Remember that it must be at night, when the symptoms will be relieved and the next day will be fine; ? 1 1. The hair dryer blows at the label, and when the glue of the trademark is hot, the label is easily torn off; ? 12. If you are afraid of wrinkling when traveling with clothes, you can roll up everything; ? 13. Drinking vinegar when burping will get immediate results; ? 14. Eat something that smells bad, such as garlic and stinky tofu, just eat a few peanuts; ? 15. Treat cough, especially dry cough. Before going to bed at night, fry eggs with pure sesame oil, add a little more oil, and don't put any seasoning. Sleeping in hot weather and eating for several days have obvious effects; ? 16. MM with long and thick wrists cannot wear thin bracelets. You should put a plastic bag on your hand and wear a bracelet. It's very easy to wear and won't hurt your hands. Take it off in the same way; ? 17. Chestnut skin is difficult to peel. Peel off the shell first, then turn it in the microwave oven, take it out while it is hot and rub it, and the skin will fall off; ? 18. When arranging flowers, drop a drop of detergent in the water for several days; ? 19. Steam walnuts in a pot for 10 minutes, then take them out and break them in cold water to take out the complete peach kernels; ? 20. Put the shrimps in a bowl, add a little salt and edible alkali powder, rub them with your hands for a while, then soak them in clear water, and then rinse them with clear water, which will make the fried shrimps transparent as crystal, refreshing and delicious; ? 2 1. When frying meat, first soak the meat in baking soda water for more than ten minutes, then pour out the water and try it again. It will be tender and smooth when fried; ? 22. Soaking the remaining tea leaves in water for a few days and then pouring them on the roots of plants can promote the growth of plants; ? 23. Dry the remaining tea leaves and smoke them in the toilet or ditch, which can eliminate the stench and drive away mosquitoes and flies; ? 24. uncooked rice re-cooking method: you can use chopsticks to tie some holes in the rice that go straight to the bottom of the pot, sprinkle a little yellow wine and stew it again. 25. If it's just a noodle clip, turn the noodles to the middle and simmer; ? 26. Clever removal of greasy screen windows: Put the cigarette butts left after washing clothes and smoking in water, and use them to clean glass windows and screens after dissolution. The effect is really good; ? 27. As long as you put a small piece of chalk in the jewelry box, you can keep the jewelry shiny; ? 28. Self-adhesive traces on the surface of tables and bottles can be wiped with wind oil essence; ? 29. Always carry a small dry battery in your bag when you go out. If the skirt is charged with static electricity, wipe the battery positive electrode on the skirt several times to remove static electricity; ? 30. No matter where your shoes rub your feet, you should apply a little white wine to the place where your shoes rub your feet to ensure that you don't rub your feet. ? 3 1. When mixing vegetables, if you have to blanch, you'd better make full use of the water for blanching good dishes.
If you cook jiaozi, you can put a proper amount of water in the meat stuffing, which not only ensures the nutrition, but also makes the dumpling stuffing delicious and fragrant. ? 32. In summer, feet are prone to sweating. Soaking feet with light salt water every day can effectively deal with sweaty feet; ? 33. Sunbathing after swimming in summer can prevent diseases such as skin strain; ? 34. In summer, pillows are prone to damp and mildew, and frequent contact with pillow cores is good for health; ? 35. Eat more wet spleen such as glutinous rice porridge, which can prevent heatstroke and damp; ? 36. Anti-insomnia: Talk less before going to bed, avoid drinking strong tea, don't use your brain before going to bed, and wash your feet with hot water and vinegar; ? 37. Honeysuckle has the effect of dispelling wind and dampness. Honeysuckle can be mixed with honey to relieve summer heat after being decocted in water to cool the juice; ? 38. Drinking tea after eating too greasy food can discipline nerves and promote fat metabolism; ? 39. Lack of sleep will make you stupid. You need to sleep for eight hours every day. Having a nap habit can delay aging. ? 40. Hands tend to become dry and rough. Soaking your hands in vinegar for ten minutes can protect your skin. ? 4 1. Wipe the mat in summer, and wipe the mat with water dripping from flower dew, which can keep the mat fresh and clean. Of course, it is best to wipe along the grain of the mat, so that the toilet water can penetrate into the grain gap of the mat, so that the cool and comfortable feeling will last longer; ? 42. Eating more acidic fruits and vegetables such as tomatoes and citric acid for breakfast is beneficial to nourishing the liver; ? 43. When washing your hair or taking a bath, adding five or six drops of toilet water to the water can play a good role in cooling and sterilizing, eliminating malnutrition and relieving itching; ? 44. Grapes contain sleep-promoting hormones, which are helpful for sleep when eaten regularly; ? 45. Drinking tomato soup in summer can not only get nutrition, but also replenish water. Tomato soup should be cooked and cooled before drinking. Lycopene contained in it has certain anti-prostate cancer and myocardial protection effects, and is most suitable for men to eat. Eating acidic substances and brushing your teeth immediately will damage your teeth health; ? 46. When the flesh is broken due to trauma, apply toothpaste to the wound to diminish inflammation and stop bleeding, and then bandage it. As a temporary first-aid medicine, medicinal toothpaste has the most remarkable effect; ? 47. Spraying white vinegar on the chopping block and washing it for half an hour can not only sterilize but also deodorize; ? 48. Drinking yogurt can relieve irritability after drinking. Yogurt can protect gastric mucosa, delay the absorption of alcohol, and is rich in calcium, which is particularly effective in relieving irritability after drinking; ? 49. When leather shoes are moldy for a long time, you can wipe them with a soft cloth dipped in alcohol and water (1: 1). ? 50. When you have a headache or dizziness, you can apply toothpaste to your temples, because toothpaste contains menthol and clove oil, which can relieve the pain; ? 5 1. Insert the candle into the birthday cake after freezing for 24 hours, and the candle oil will not flow down when it is lit; ? 52. White underwear turns yellow easily after washing. You can take a basin of water and drop two or three drops of blue ink. Soak the washed underwear for a quarter of an hour and put it in the sun. It can be white and clean without wringing it out. ? 53。
4. Little scientific knowledge
Why do the stars twinkle? We see the stars shining, not because the luminosity of the stars has changed, but because of the occlusion of the atmosphere. The atmosphere is between us and the stars. When starlight passes through the atmosphere, it will be affected by the density and thickness of the atmosphere.
The atmosphere is not absolutely transparent, and its transparency will change according to its density. So when we look at the stars through it on the ground, we will see that the stars seem to be flashing.
2。 Why do people yawn? When we feel tired, a lot of carbon dioxide has been produced in our bodies.
When there is too much carbon dioxide, oxygen must be supplemented to balance the needs of the body. Because these residual carbon dioxide will affect our body's functional activities, then the body will send out a protective reaction, so we yawn.
Yawning is a deep breathing action, which will let us breathe in more oxygen and expel more carbon dioxide than usual, and it can also eliminate fatigue. 3。
Why can snakes walk without feet? Snakes have many scales, which are the outermost armor on their bodies. Scales are not only used to protect the body, but also to be their "feet".
When a snake crawls forward, its body will be S-shaped. Every scale outside the S-shape will tilt upward to help the snake catch the uneven road when it moves forward.
These scales cooperate with the muscles of the snake and can push the body forward, so the snake can walk without feet! 4。 Why do sunflowers always bloom towards the sun? There is a substance called "auxin" in the stem under the sunflower disk.
This substance has the function of accelerating replication, but it is anti-optical, and it will run to the backlight side whenever it encounters light. So when the sun rises, the stem of the sunflower immediately hides to the side of the backlight, as if the whole plant is bent in the direction of the sun.
5。 Why does the hair turn white when people are old? There is a substance called melanin in our hair. The more melanin, the darker our hair will be.
Without melanin, hair will turn yellow or white. When human beings reach old age, various functions of the body will gradually decline, and the formation of pigments will be less and less, so the hair will gradually turn white! 6。
Why do fireflies glow? Fireflies emit light because there is a luminous body at the end of their abdomen, which is filled with a lot of phosphorus-containing luminescent substances and luminescent enzymes, so that fireflies can emit flashing light. The purpose of fireflies is not only lighting, but also courtship, vigilance and trapping.
This is also a communication tool for them. Different kinds of fireflies emit light in different ways, frequencies and colors, so they can convey different information. 7。
Why do you growl when you are hungry? When you are hungry, you will purr. This is because the food you have eaten before has almost been digested. Although the stomach is empty, the gastric juice in the stomach will continue to secrete. At this time, the contraction of the stomach will gradually expand, and the liquid and gas inside will be stirred up and purr.
Don't be embarrassed by your stomach growling next time! Because this is a normal physiological action. 8。
Why can't ostriches fly? A giant ostrich, but they can't fly into the sky! This is not because their wings are useless, but because their feathers are too soft and their wings are too small to fly at all. In addition, the ostrich's muscles are underdeveloped and its sternum is flat, which is not conducive to flying.
Ostriches live in Africa. Because they have lived in desert areas for a long time, their bodies gradually evolved into what they are now in order to adapt to the environment. 9。
Why can't it go bad easily? Lunch meat, black bean shad, tomato sauce beans.
They are all delicious canned food, which can be preserved for a long time without deterioration. This is because the can is sealed, so bacteria can't enter.
When people make canned food, they pump all the air out of the canned food and then seal it. In the absence of air, even if the food inside is contaminated with a little bacteria, they can't survive or reproduce! 10。
Why do babies always cry at birth? Babies cry when they are born, not because they are unhappy, but because they are taking the first breath of air! When babies leave their mother's body and are born, the first breath of air will rush to their throats, violently impact the vocal cords, make them vibrate, and then make a sound similar to crying. 1 1。
Why do lizards keep playing backwards when their tails are broken? In order to protect themselves, many lizards also protect their eyes and ears; When some lizards are attacked, their tails will be broken due to the severe contraction of their muscles. Because there are still some nerves alive in the broken tail, it will keep bouncing, thus distracting the enemy and running away.
Don't think that their lives will end like this. In fact, it only takes a few months, and their tails will grow back and move on. 12。
Why is the squirrel's tail so big? Don't look at the relaxed mouse tail! When the squirrel jumps around the tree, its tail plays a great role. It can keep balance when the squirrel jumps to the tree to avoid falling and being injured.
In addition, this big tail can play a more protective role in winter, tightly surrounding the squirrel's body, which is convenient and practical. 13。
Why can't a person's thumb have one or three knots? The average person has five fingers, each with a different length. However, does anyone realize that besides the thumb, other fingers also have three sections, while the thumb alone has only two sections? It turns out that the number of joints is just the same as the other four fingers.
If it is three knots, the thumb will appear weak, so that it can't lift heavy objects; If there is only one section, it can't grasp things freely with the other four fingers! 14。 Why not tickle yourself? When others scratch ourselves, we will feel itchy and laugh constantly; However, when we scratch ourselves, we not only don't laugh, but also don't itch.
Based on our psychological preparation, the brain will send out a message that there is no danger, and the nerves will relax, so that they will not laugh and itch! 15。 Why is the sea mostly blue and green? Looking at the sea, it is often found that the sea water is blue-green.
However, when you pick up the sea water, you can only see it as transparent and colorless as old water. Original.
5. What is the difference between scientific knowledge and common sense?
Usually when we say that a person has knowledge, do we mean scientific knowledge or common sense? What is the difference between scientific knowledge and common sense? Let's get to know each other by comparison. A. In the northern hemisphere, the height angle of the sun is greater in summer than in winter. B.the sun is stronger in summer than in winter. Conclusion: A is scientific knowledge and B is common sense of life. If you know A, it means that you have a lot of scientific knowledge, which is true knowledge. If you don't know A, but you know B, it means that you know common sense of life, but lack scientific knowledge, that is, you are not very knowledgeable. Analysis: It is scientific knowledge to say that "in the northern hemisphere, the solar altitude angle in summer is greater than that in winter". The reasons are: (1) This statement can be verified by observation and does not change with the weather and climate; (2) The definition of "solar altitude angle" (the angle between the observation point and the sun and the horizon) is clearer than that of "violent", so you can repeat the observation and compare the results. (3) The applicable conditions of "in the northern hemisphere" are very necessary, but this phenomenon does not exist in the southern hemisphere. It can be seen that the saying that "the sun is worse in summer than in winter" is just common sense, not scientific knowledge.
6. Encyclopedia of scientific knowledge (30 words)
Scientific common sense in life:
1. Why does sorbet get angry?
The reason why sorbet bubbles is because there is a lot of invisible water vapor in the outside air. When it comes to cold sorbet, it will liquefy into droplets when it is cold. It seems that the sorbet is bubbling.
2. Why do sunflowers always face the sun?
Sunflower stems contain a wonderful auxin. This auxin is very afraid of light. When it is illuminated, it will go to the backlight side, and the cells on the backlight side will multiply rapidly. Therefore, the backlit side will grow faster than the bright side, which will bend the sunflower to light.
3. Why do cicadas shed their skin?
Cicada's shell (exoskeleton) is hard and can't expand with the growth of cicada. When the cicada grows to a certain stage, the cicada's exoskeleton restricts its growth, and the cicada loses its original exoskeleton, which is cicada slough.
4. How do bees make honey?
Bees spit the collected sweet flower juice into an empty beehive. At night, they suck sweet juice into their honey stomachs to make it, and then spit it out and swallow it. It takes 65,438+000 ~ 240 times to make sweet honey.
5, hanging on the wall of the quartz clock, when the battery runs out and stops, its second hand often stops at the "9" position on the dial. This is because the second hand is most hindered by the large torque at the "9" position. Scientific common sense
6. Sometimes, when tap water flows from the adjacent faucet, it occasionally makes bursts of noise. This is because the water pipe vibrates when the water rushes out of the tap.
7. When taking pictures on TV, turn off the camera flash and indoor lighting to make the picture clearer. Because the reflected light of the flash lamp and the illuminating lamp on the TV screen will interfere with the transmitted light of the TV picture.
8. At the same temperature, frozen meat thaws faster in water than in air. At the same temperature, hot nails cool faster in water than in air. A cup filled with boiling water cools faster when immersed in water than when immersed in air at the same temperature. All these phenomena show that water has better heat transfer performance than air,
9. When there is cold water in the pot, the water droplets attached to the outer surface of the pot bottom can only be dried up after a long time on the flame, and will only boil when it is dried up. This is because the water droplets, the pot and the water in the pot keep heat conduction, and the temperature is almost the same. As long as the water in the pot is not boiled, the water droplets will not boil, and the water droplets will evaporate on the flame and be gradually dried up.
10, out-of-shape mirror, the farther away from the mirror, the more out of shape. Because the image in the mirror is formed by the reflection of the silver-plated surface behind the mirror, uneven silver-plated surface or uneven glass thickness will lead to aliasing. The farther away from the deformed mirror, the more the reflected light on the silver-plated surface deviates from the normal position according to the principle of light amplification, and the more deformed the mirror is.