Small scientific papers (8 papers) 1. Why can white vinegar show words? I read in a science book that white vinegar can show words. I don't believe it. White vinegar is white, so it won't print. Maybe there is something wrong with this book. Hey! Only by doing this experiment can we know. I quickly found a candle, a piece of A4 paper, a lighter, a brush and a bottle of white vinegar. I dipped my brush in white vinegar for a few times, and then wrote the four characters "Wu Jia is really small" on A4 paper. At first, there was a watermark on it. After a while, there was nothing on it. It is as white as new. I thought: If this word is gone, how can it be displayed in brown? No way! No way! I lit a candle and put paper on it to bake. At first, I almost burned all the paper. I put it on it carefully again. Suddenly, a brown curly hair appeared in the place where "Wu" was written. I'm surprised. How come... How can there be brown curly hair without words? I continued to bake, and slowly the small words appeared. The words on it are brown and a little black. The place where the word "true" was written was burnt out because it was badly baked. Everything in the original book is right! It is said that this method was used in the past to prevent the enemy from discovering it. It is really convenient and safe. Why can this be printed? I looked it up in the book. It turns out that white vinegar is like burning when it meets high temperature, just like printing. I see! Ah! It turns out that the mystery of science is so magical. Since then, I have developed a strong interest in experiments, and I will do more experiments and uncover more scientific mysteries in the future. 2. Why should trees be painted with white paint? I have a good habit of taking a walk after supper, but whenever I take a walk, I always see rows of trees painted with white paint on the roadside, which is very spectacular. But why should the bottom of the tree be painted with white paint? Thinking of this, I ran home and asked my parents. Father said, "It's for environmental protection." But my mother said, "The workers have nothing to do." "Is this really the case?" In order to find out. When I came to my grandmother's house, I found two trees in her backyard that had not been painted white and were still tall and straight. So, I came up with the idea of doing experiments! Thinking of this, I asked my mother to buy a bucket of white paint and my father to bring a brush. Everything was ready, and I started to act, holding a brush stained with white paint like a worker's uncle and brushing the tree. From then on, I went to my grandmother's house to see these two trees every day. The following is my investigation report: Leaves: Five days later, the leaves of the trees painted with white paint became greener. Similarly, five days later, I observed that the leaves without white paint turned yellow. Branches: Three weeks later, I looked at the white painted tree again and found that the branches were very strong. Similarly, after three weeks, I found that the branches without white paint were not very strong, and they would break if they were folded hard. Summary: It turns out that trees painted with white paint are stronger than those not painted with white paint. "Is it really a tree painted with white paint?" But I still didn't believe it, so I went to the computer, a knowledgeable person. From the computer, I know that the original tree is not painted with white paint, but with lime. Lime has a certain bactericidal and insecticidal effect, which can kill some overwintering fungi, bacteria and pests parasitic on the trunk. In winter, some pests on trees will drill underground for the winter. If you apply lime in autumn, it won't come down, and you will freeze to death in winter. Brush it again next spring, and insects that hibernate underground will not easily climb up the tree to do harm. Because lime will dehydrate insects to death, they will all stay away. Oh, I see. No wonder the trees are covered with lime every autumn.

3. The secret of iron sheet

We learned Tin Pots and Pots, knowing that tin pots rot easily in the soil, and a little question mark popped up in our mind: So where does iron rust fastest? To this end, I made a small experiment after repeated thinking and research. I prepared three small pieces of iron in advance. One is placed in a place with low temperature-refrigerator; One is buried in the soil; The last one was put in salt water. Let's see which will make the iron rust faster. At the end of the day. Before I came to the refrigerator, I carefully took out the iron sheet and observed it carefully. The iron sheet hasn't changed at all. I then went to the flowerpot and dug out the iron pieces hidden in the soil, and the result was still the same. Finally, I came to the cup and took out the iron piece soaked in water, but there was no change at all. This annoys me: "Will it take a long time to have an effect?" I left the experimental site with questions. A few days later, I went there again and was surprised to find that the iron sheet in the soil was a little rusty, while the iron sheet in the salt water had rusted. What the hell is going on here? With this question, I turned on the computer and realized that it was the reaction of the primary battery, and the ions were conductive. Because two metals usually have different activities. Take iron and copper for example. Because there is moisture in the air, water usually contains acidic gases, such as carbon dioxide. When the iron sheet encounters acid, it loses electrons and becomes iron ions. The electrons move to copper through the metal, and then are reduced to hydrogen to form primary electrons. This reaction is called hydrogen evolution reaction. This corrosion of iron is called electrochemical corrosion, and the electrochemical corrosion rate is faster than that of general oxygen reduction corrosion. Experiments and data prove that salt water will make iron rust faster!

4. How strong is the regeneration ability of earthworms? I remember when I was a child, we often went to the river to catch earthworms and then went fishing. I remember that the earthworm was still moving after we cut it into four or five sections. A few days later, when I went fishing again, some earthworms died while others got into the soil. We are very puzzled about the regeneration of earthworms, but we have consulted many students, and they are as unclear as we are. Therefore, we decided to study the mystery of earthworms. I got a lot of answers in a biology book: Earthworms, like geckos, all contain biological organs-regenerative organs, which can make earthworms decompose and secrete a yellow sticky substance to wrap the wound, so that earthworms can come back to life. If we don't find the reproductive organs of the earthworm, the life and death of the earthworm is still a mystery, so we rushed to a small ditch with tools and grabbed the earthworm. We first came to a fertile land, caught two earthworms and put them on the board, then took a sharp scalpel from home, found the middle of the earthworms and cut them down. We cut the earthworm into two pieces, and the earthworm rolls on the board, sometimes some mucus will flow out, which will stop bleeding and regenerate the wound of the earthworm. Earthworms will release mucus, and at the same time, their bodies will shrink continuously, and finally they will be wrapped into a shell. Then we put the second earthworm on the board and cut it into four sections with a scalpel. In this way, some of them move and some don't, and they also release mucus to repair damaged bodies. Based on these, I come to the conclusion that earthworms have strong wound healing ability. 2. Earthworms have a strong regenerative ability, and organs with simple structures can grow back after being cut off. However, it is difficult for organs with complex structures to grow back after being cut off.

5. Why are leather shoes getting brighter and brighter? Why are leather shoes getting brighter and brighter? This question has been bothering me for a long time. Until today, I finally solved the mystery. I remember once, my mother and I went shopping and passed by KFC. I saw an aunt polishing a gentleman's shoes. I am curious. I stared at my shoes and stood by. I saw that the aunt wiped off the dust on the vamp first, then applied shoe polish and polished it carefully. Shoes become bright and beautiful. But why is this? I'm being weird?

When I got home, I found the old leather shoes worn by my father and a pair of new leather shoes bought by my father. I first touched the uppers of two pairs of leather shoes and found that the surfaces of the new shoes were smoother than the old ones. Later, I painted my old leather shoes with shoe polish and brushed them carefully with a brush. I found that they are much brighter than the original ones, but they are still not as good as the new ones. Is the brightness of leather shoes related to the uppers of leather shoes? I am lost again. I brought another pair of old leather shoes and touched the vamp with my hand. I felt that the vamp was uneven. Then, I touched the leather shoes with my hand, which had two rough surfaces. I put shoe polish on a rough surface, and the rough surface immediately became very shiny. Why is the difference so big? I decided to look up information on the internet. It turns out that this is the result of the comprehensive function of shoe polish reflecting light and shielding. What makes the leather shoes brighter and brighter is that the shoe polish fills the pores of the upper and wipes off the raised grain surface, making the upper become a mirror that tends to be flat, and the light reflection of the oil will make it brighter and brighter. But this kind of behavior makes shoes shine, but it closes the pores of the dermis, which is tantamount to the rich tying themselves up, which is actually not conducive to people's health. This is the sorrow of mankind. Oh, I see. I finally know that the more shoes are polished, the brighter they are. At the same time, I want to remind you not to damage your health in order to polish your shoes. I really want to thank an insider at home, a doctor of computer science, for teaching me so much knowledge! 6. Why does the thermos bottle jump?

"Poof", a loud voice came, what's going on! It turned out to be the sound of the cork of a thermos bottle jumping up. Why did the cork suddenly jump up? I have doubts about this and am determined to explore this mystery. So, I brought two thermos bottles and a bottle stopper, one for boiling water and the other for tap water. First of all, I carefully blocked the bottle mouth full of boiling water with a cork. After a while, I heard a "poof" sound, and the hot water cork suddenly jumped out of the bottle mouth, and the boiling water splashed out. It was time to try another bottle, so I blocked the cork of the thermos bottle with tap water. However, after a long time, the cork stopped moving at all, so it couldn't jump. After the experiment, I came to a conclusion that boiled water can make the cork jump. However, what kind of scientific truth is there? So, I went to find a lot of information, and finally, I found this reason. It turns out that the water in the thermos is hot. When you plug the cork, a lot of air enters the empty space of the thermos. When air is heated, it will expand rapidly. At the same time, hot water will continue to generate hot steam. The expanding air and hot steam jack up the hot water bottle stopper.

7. How to keep the towel from hardening One winter morning, I got up and went downstairs, went into the bathroom, pulled the towel down and touched it. Hey! What happened? Why is the towel hard? I'm confused. I said to myself, "It was still wet yesterday. Why is it so hard today? I can't help but ask a question mark in my heart. " When I came home from school at noon, I saw my mother drying towels. It just occurred to me that the towel has hardened. Busy asked his mother: "Mom, why do towels become hard and rough in winter?" Mother said, "It's so cold that the towel will harden after a long time." After listening to my mother's words, I will be dubious. I still have some doubts about whether what my mother just said is true. In order to solve this mystery, I personally went out and turned on the computer to check. It turns out that the towel is just because there is a substance "fatty acid" in the soap on the towel. Because of the cold weather and rough towels, it is easy to rub the towels. Calcium and magnesium in water combine to form a substance that is insoluble in cold water. Oh, I see. I suddenly realized. But how can we keep the towel from hardening? By the way, I can do experiments to verify it. I brought two new towels, one with soap and the other with hot water. After a day, I couldn't wait to come to the bathroom. At this time, I found that the towel washed with soapy water had hardened, but the towel was still the same. Through this experiment, it is proved that science is proved by practical activities, not in name only.

8. Can water shine? As the source of life, water can be seen everywhere. Without water, people can't eat, wear, live and travel. But can water shine? Today, the teacher asked us such a question. We don't know how to answer. The teacher said, "Let's do an experiment today to see if the water will glow?" The teacher gave us two kinds of water, one is distilled water and the other is tap water. We put two kinds of water in beakers respectively and put them according to the picture. At the moment when we turned on the power, something magical happened. The diode plugged in tap water is on, and the second machine tube plugged in distilled water is still the same, without any phenomenon. We all opened our curious eyes and turned on and off the power supply. We began to wonder if there was something wrong with the diode. We replaced it with a new one, and the result is still the same as the above phenomenon. Why is this happening? A big hello appears in our minds. Suddenly, a classmate said, "See if we got it wrong." We checked one side carefully, but there is still no problem. What's the problem? Suddenly a classmate whispered, "Is there something wrong with the water?" This sentence reminds us that "on the right is water, one is distilled water and the other is tap water". At this time, the teacher smiled and said, "Everyone is right, it's the water." I'm asking you a question: "Why is the phenomenon different when the water is different?" We all stared at each other and began to think hard. "Distilled water is clean, nothing is dirty, tap water is not clean, and there are many dirty things." The teacher nodded and said, "It's basically said, but it's not accurate enough. Everyone knows that distilled water is clean. We call it pure, that is, it contains only water molecules and no other substances, so it does not contain conductive substances (ions), so the diode does not emit light. " Before the teacher finished, a classmate inserted a sentence: "Tap water is unclean and contains charged substances (ions), so it can conduct electricity and the diode will emit light." We heard that the clouds in our hearts finally cleared here. Through this experiment, I understand that water itself does not emit light, but some water can conduct electricity and make diodes emit light. And not all water can conduct electricity, which can make diodes glow. Tap water can conduct electricity and make diodes glow because there are conductive ionic substances in tap water. Distilled water can't conduct electricity, but it can make the diode glow, because there is no conductive ionic substance in it. I know why I can't put out the fire with tap water when the power supply and wires are on fire, otherwise it will generate electricity and get an electric shock.