1 Can you put out the fire from a distance? Impossible, right? Did it explode? However, the power of science can always make the impossible possible. Fire fighting in the air is no longer an imagination. This time, the teacher feasted our eyes.
The teacher first sets up the experimental equipment: a beaker, a bottle of baking soda, a bottle of citric acid, a "fire source" candle and a cup filled with water. As soon as the equipment was put on the table, everyone began to talk about it and guess the experimental results. After the teacher lit the candle, we couldn't wait to operate it. We were divided into two groups. First, mix and stir two spoonfuls of baking soda and two spoonfuls of citric acid. Our "operator" carefully picked up the spoon and began to scoop it, for fear of any mistake. We also stared at them with wide eyes. After the operation, the teacher said mysteriously, "Next, we add half a glass of water to the cup, and then tilt the cup quickly to get close to the fire source. The first group did the experiment first. After he poured the water into the cup, he slowly approached the fire source. The flame trembled and emitted a wisp of black smoke, but it didn't go out. The experiment of the first group ended in failure. I can't help but get nervous; The first group of experiments failed, so may we. The success of the experiment can only depend on our group. At the beginning of our group, trembling hands picked up the cup, and the flames began to tremble, which seemed a little scared. We all held our breath and poured water into the cup, and the bubbles began to pop up instantly, just like soda, and there was a bad smell at the same time. The players immediately leaned their cups against the flame. The flame that was arrogant just now, under the fierce offensive of bubbles, struggled violently, emitted a wisp of smoke and went out! I can't help cheering in my heart. At the same time, I am thinking: What makes the flame so fragile that it can "attack" the flame from a distance? When the teacher asked, a classmate mentioned carbon dioxide, and the problem in my heart was solved immediately. Baking soda reacts with citric acid and becomes carbon dioxide. When the carbon dioxide in the cup is poured into the fire source, the fire source will be extinguished because it is blocked by oxygen. This is really amazing!
Fire can burn everything, but unexpected and terrible fire can be defeated by small carbon dioxide! Science is really amazing!
Every time I see my father pouring beer, I always see that when it is almost full, my father will slow down until the glass is full. I found that at this time, the water surface will form a slightly arched arc, and I always feel that beer will overflow from the cup immediately, but it doesn't overflow every time. I think it's strange.
I ran to ask my mother. My mother said to me, "Not only will this water not overflow, but it won't overflow if you put something in it. Do you believe it? " "I don't believe it!" I looked puzzled, so my mother and I did a small experiment together.
Mother asked me to prepare a glass and a box of paper clips. I filled the cup with water first, but it also fell into the water and became a small arch. The water seems to have overflowed, but it didn't. I took out a paper clip and carefully put it into the water. Sure enough, the water didn't overflow. I thought, "Just a paper clip, it's too little. Maybe put four or five more and the water will overflow. " I put five more in a row, and the water hasn't overflowed yet. I am very unwilling to continue the test.
When I put it in block 100, there was still not a drop of water. Careful observation shows that the water surface is fuller, as if something in the water is struggling to break the water surface, but the water surface is like a film, which can't be broken. I was dumbfounded, but I didn't know what the principle was.
My mother asked me to check the information, and I realized that it was because water had a certain viscosity and surface tension. Even if a paper clip is put into a full glass of water, the water level will rise, but due to the viscosity between water molecules, the water at the edge of the cup will remain continuous. Therefore, if the volume of the object put in each time is small enough, the water surface will swell due to tension, so it will not overflow. Unexpectedly, the seemingly ordinary water is so magical!
At the end of the experiment, I exclaimed: I didn't expect a glass of water to have such great knowledge! We should get tips from small experiments in life, so as to learn to live better.
I did an interesting little experiment for my classmates today-blowing bubbles. This experiment is very simple, only a small bottle, a little water, a few drops of detergent and a thick straw are needed.
I put these items on the table and my classmates looked at me curiously. What experiments can these things do? I pour the water into a small bottle prepared in advance, and then pour the detergent into the water. Then, I put the prepared straw into the water, stirred it clockwise for a few times, and then carefully took it out. I looked at everyone, and they all looked at me intently. At this time, I took a deep breath and gently blew it into the straw. Suddenly, a small bubble appeared at the other end of the straw. The students looked at this round, crystal-clear little bubble and suddenly became interested, and they were all eager to try. So, I sent the straws prepared in advance to everyone, and everyone blew out a lot of bubbles. Suddenly, colorful bubbles floated in the classroom and became a bubble world. At this time, I don't know who asked: "Why are bubbles blown out?" Yes, why? You look at me, I look at you, and then ask the teacher for help.
The teacher looked at everyone puzzled and said with a smile, "I'll tell you the reason for the formation of bubbles." When water and detergent are mixed together, the surfaces of water molecules and detergent molecules are sticky, forming tension. The mutual attraction between molecules on the water surface is greater than that between water and air, just like sticking together. If water molecules are excessively combined, bubbles will not easily form. Detergent' breaks the surface tension of water and reduces the surface tension under normal conditions to only 1/3, which is the best tension required by bubbles, so bubbles are formed. "
The students all nodded after listening. This experiment is really interesting! Unexpectedly, a simple experiment contains such profound scientific truth!
Today, the weather is clear and there are no clouds in Wan Li. The sun selflessly shines bright light on the earth.
The third period is a general knowledge class. As soon as the students entered the classroom, they saw several washbasins and mirrors on the podium and thought, what experiment is the teacher going to do for us?
After sitting down, the teacher asked us, "What color is the sunshine?" Hearing this question, the students stuck their heads out of the window in unison. At this time, the bright sunshine is shining into the classroom through the glass window. Li Wei stood up and said, "Let's see! The sunlight should be white. " Zhou Wei put forward a different opinion: "I said,' The sun should be red. Because one night in the morning, the sun dyed the whole sky red. The teacher said, "Now let's do a little experiment to see what color the sunlight is."
The teacher divided us into four groups, each group was given a washbasin and a mirror, and asked the group leader to put half a basin of water in the washbasin. The teacher asked us to aim the mirror at the window first, let the sun shine on the mirror, then reflect the light into the water with the mirror, and then the water in the washbasin reflects the sun onto the wall. Only in this way can we see the true color of sunlight.
As soon as the teacher's voice fell, everyone was too busy to think there were too many cooks. Li Wei is the fastest. He pointed the mirror at the window, and a beam of sunlight shone on the mirror, but the mirror did not reflect the sunlight into the water, but reached the ceiling. Zhou Wei a look nasty, hurriedly move the washbasin, almost spilled water in the body. However, after moving several positions continuously, the light reflected by the mirror did not fall into the water. "This ... this ... I can't move the washbasin to the ceiling!" Zhou Wei was tongue-tied. At this moment, the teacher came up to Zhou Wei and said, "The problem is not you, but Li Wei put the mirror face up." When he said this, he called Li Wei: "You lift the mirror, and the mirror is facing down." Li Wei did as he said, and sure enough, the mirror reflected the light into the water, and the water in the washbasin reflected to the wall. Ah! I saw it! I saw it! Snow-white walls show seven colors: red, orange, yellow, green, cyan, blue and purple. How beautiful! At this time, several other groups also did experiments, and the walls were full of seven-color light spots.
What an interesting experiment of sunlight scattering! Li Wei suddenly realized: "Oh, I see, after the rain clears, the rainbow in the sky is formed by the refraction of sunlight!" "
A piece of paper can draw pictures, and a piece of paper can be made by hand, but do you believe that a piece of paper can hold up twenty books? Let's wait and see!
At the beginning of class, the teacher said mysteriously, "Students, I can make this paper in the teacher's hand hold up twenty books!" " "Hearing this, the students suddenly exploded. The students talked about it in succession, and all thought that the teacher was bragging. My second monk is at a loss. I wonder what medicine the teacher sells in the gourd. The experiment is about to begin. The teacher gave each of us a piece of paper, the requirement is: make a fuss on the paper, without any assistance, so that this paper can hold up the book. When the teacher announced the requirements of the experiment, I carefully observed every expression of the teacher and every word he said, for fear of revealing some clues and failing my little Sherlock Holmes.
I took the paper and looked around, racking my brains to find a way. Suddenly, a good idea came to my mind. I folded the paper into a fan and carefully put the first book on it. The book stood firmly on the paper, and my hanging heart finally fell down. Then I put the second book on it. Unfortunately, all the books collapsed with a bang. I am sad. Why did I fail? But on second thought, failure is the mother of success, and I started the experiment again, but no matter what I did, I just couldn't put down the twenty books the teacher said, and I was very depressed. At this time, I heard the students in other groups cheering and shouting, "I put thirty books on it!" " Teacher, I posted thirty books! "I followed the sound, and it turned out that they had folded the paper into an M-shape. I learned from my experience and quickly folded the paper into an M-shape, hahaha, I also succeeded.
What puzzles me is why paper can be folded into an M shape to hold many books. After the teacher's explanation, I finally understood that when the number of folds of paper increases, the bearing capacity of paper becomes larger, and the bearing capacity of paper is related to the shape of paper.
This lesson made me understand that we should observe and think more in our daily life in order to discover more mysteries.
Can 6 stitches float on the water? Can the needle "backstroke"?
Today I did an interesting little experiment-the needle floated on the water.
Every household has a needle, but how can it float on the water? I was curious and started the experiment. First, prepare a sewing needle, a big bowl filled with water, an ordinary napkin and a toothpick for my mother.
I spread the napkin flat on the table first, and then put the needle on the napkin; Then, I picked up both ends of the napkin with both hands and gently put it on the water with the paper tape needle. Suddenly, the white napkin became transparent and floated evenly on the water. I couldn't wait to pick up the toothpick and take it out of the bowl. I didn't expect the needle to fall into the bottom of the bowl and the experiment failed. I think it is possible that the paper is not completely saturated.
The second experiment began, and this time I was not as anxious as last time. After the four corners of the napkin sank, I saw that the middle part of the paper was still motionless, and the needle and the paper were still tightly together. So, I picked up the toothpick, gently pressed the napkin into the water, and then gently fished it out of the bowl with the toothpick. I did it very carefully, and I didn't even dare to blink, for fear of touching the needle. When the napkin was completely fished out of the water, I saw the needle floating firmly on the water. I am happy to take a toothpick and say loudly, I succeeded! I made it!
But why can the needle float on the water?
Then I thought of the computer, so I looked it up on the Internet. It turns out that the surface of water has a certain tension, and the surface tension of water supports the needle, so the needle will not sink. I know that needles can float on the water. Seeing the sewing needle floating freely on the water, my heart is really unspeakable.
It turns out that a small sewing needle has such a big mystery. You must do more experiments in the future to enrich your knowledge and bring fun to yourself.