Not long ago, our family moved into a new house. Just moved home, my uncle and aunt sent some pots of flowers and trees. Bonsai is placed at the door, living room, room and balcony. I said to my father, "We have a botanical garden at home. Why do we have so many plants? " Dad smiled and said, "Plants can create an atmosphere and purify the air. People and animals cannot do without them. " People or animals cannot live without plants? Why can't people or animals live without plants? I'll be skeptical. Decided to do a few small experiments to prove the problem.
On Sunday, I caught two mice from the garage. These two poor little mice will be my experiments. They have been struggling, and the round disposable film tablecloth stared at me with small eyes. I put the first mouse in a big fish tank and sealed the glass bottle tightly, for fear that the air in the bottle would communicate with the outside air. I watched carefully and saw the little mouse running quickly around the bottom of the cylinder against the wall. Hey, isn't the mouse alive and well? Isn't it true what dad said? However, in a few minutes, I saw the little mouse winding slower and slower until it was stagnant and dying. Suddenly, I gently removed the disposable film tablecloth, grabbed the first mouse, put the second mouse in, and moved into four pots of leafy plants. Then gently cover the disposable film tablecloth. I kept patting the fish tank and saw the little mouse scurrying about in panic. After a long time, I don't want to die. This experiment proves that plants can transport the oxygen that animals need.
In order to further prove the dependence of humans and animals on plants. I came to a feed processing factory near our hometown. The air there is full of dust noise, which makes me cough. I feel very uncomfortable. Then, I ran to a bamboo forest behind our house. It is a place with fresh air, and I feel extremely refreshing. This experiment proves that plants can purify the air. Let people breathe smoothly.
These two experiments prove that the survival of human beings and animals is closely related to plants. How scientific is this? Our scientific and technological team came to the library to consult a lot of scientific and technological books, and also went to the electronic north reading room of the school for online inquiry, and summarized the following points: ① People must rely on plants to provide oxygen, and only plants can make oxygen. If a person doesn't eat or drink for a few days, he may die in a few minutes. Oxygen is the first need of human life activities! An adult breathes about 20,000 times a day, inhaling 0.75 kg of oxygen and exhaling 0.9 kg of carbon dioxide. (2) Breathing of animals and plants and burning of substances also consume oxygen and release carbon dioxide. So, isn't there more oxygen in the air every day? Don't! The reason why there has never been such a crisis between heaven and earth is that plants are both "factories" of natural oxygen and "broad markets" of carbon dioxide. According to statistics, 1 hectare of broad-leaved forest can produce 750 kilograms of oxygen and eat 1 1,000 kilograms of carbon dioxide every day during the growing season. Therefore, as long as there are 6,543,800 square meters of trees, it can supply a person with oxygen demand and absorb exhaled carbon dioxide. Because there are plants that constantly supplement oxygen, the oxygen in the air can be kept basically constant. On the contrary, if there are no plants, the oxygen on the earth can be used up in about 500 years.
2. A new storage CD.
With the development of society and the progress of science, computers are no longer strange to people. Only in ordinary families in Beijing, the popularity of computers has been relatively high.
For users who use computers, how to operate is no longer difficult, but new problems have emerged. What is the storage and circulation of massive information?
Floppy disk is easy to carry, but its capacity is too small, generally less than 2MB (1MB =1000 KB =1000 KB, 2B can hold a Chinese character), which is not suitable for slightly larger software. The hard disk has a large capacity and is not suitable for slightly larger software; Hard disk has a large capacity, ranging from tens of megabytes (MB) to several GB( 1GB= 1000MB), but it can only be installed inside the machine, which is extremely inconvenient to carry. In order to concentrate their advantages and avoid their disadvantages, a new type of memory-optical disk appeared. A CD is about the size of a floppy disk, so you can take it with you at any time. The use method is basically the same as floppy disk, except that you use CD-ROM drive instead of floppy disk drive.
A CD is about the size of a floppy disk, so you can take it with you at any time. The use method is basically the same as floppy disk, except that you use CD-ROM drive instead of floppy disk drive.
Different from soft disk and hard disk, optical disk does not use high-speed rotation to control reading and writing speed, but makes full use of light. High-tech optical head reading and writing make CD-ROM and CD-ROM drive fast and large in capacity, keeping up with the current development trend of computers.
CDs are divided into two categories: read-only CDs and read-write CDs. The standard capacity of CD-ROM drive is 650MB, which is much faster than floppy disk and equivalent to the speed of mid-range hard disk. The capacity of reading and writing optical discs is larger, generally not exceeding 1.4GB, and the speed is slightly slower, which is equivalent to the speed of a low disc.
The advantages of CD are not limited to these, it has been widely used in the computer field.
First of all, the capacity of software, whether it is application software or game software, is above 15MB, so it is inconvenient to use floppy disks, let alone hundreds of gigabytes of advanced software. You don't have to worry about this when using CDs. No matter how big the software is, just a few thin CDs can solve the problem. So now the software and games tend to be exquisite and perfect, and the loopholes are obviously reduced.
Secondly, the popular CD turntables and VCD discs now adopt optical disc technology. They are essentially optical disks stored in different formats.
In addition, compared with software, hard disk and CD-ROM, it is cheaper and acceptable to ordinary families. Therefore, I believe that before long, CD will become the mainstream in the field of computer circulation, and its development will not stop for a long time.
3. The law of conservation of momentum is the earliest law of conservation, which originated from western European philosophy in 16 and 7 centuries. Descartes, a French philosopher, mathematician and physicist, made an important contribution to the discovery of this law.
Observing the moving objects around us, we see that most of them will eventually stop. It seems that the total movement of the universe seems to feed the whole universe. Is it like a machine that will stop one day? However, the observation of celestial motion for thousands of years has not found the phenomenon of weakening the motion of the universe. /kloc-Many philosophers in the 6th and 7th centuries believed that the total amount of motion in the universe would not decrease. As long as we can find a suitable physical quantity to measure motion, we will see that the total amount of motion is conserved. So, what is this suitable physical quantity?
The French philosopher Descartes once suggested that the product of mass and speed is a suitable physical quantity. Speed is a scalar without direction. It can be seen from the first experiment in the third section that the physical quantity defined by Descartes is not conserved in that laboratory. The two interacting objects are stationary at first, and the speed is zero, so the sum of this physical quantity is equal to zero. After the interaction, both objects get a certain speed, and the sum of this physical quantity is not zero, which is higher than that before the interaction.
Later, Newton slightly modified Descartes' definition, that is, instead of using the product of mass and velocity, a suitable physical quantity was obtained to measure motion. Newton called this quantity "the amount of exercise", and now we call it momentum. Descartes failed to find a suitable physical quantity to measure motion because he ignored the vector of momentum, but his work laid a good foundation for later people to continue their exploration.
4. Can you walk freely on the blade? Can you walk away from the blade and have nothing to do? Definitely not. But, you know what? A small snail can do it.
At noon, my mother put the dishes in the kitchen with some blades in front of her. A snail crawled in from nowhere, and when he saw the vegetables, he struggled to climb to them. If you want to eat green vegetables, you need to turn it over from the blade. Unexpectedly, when it passed the blade, nothing happened and it reached its destination safely. I was really surprised. I want to know if there is a "protective film" on the snail's lower body, so I study snails with a magnifying glass.
It turns out that there is a very elastic muscle under the snail's body, which is very developed and very different from other muscles. This muscle is made up of many small pieces of muscle. This muscle is the stomach foot of a snail. When a snail crawls, its feet cling to other objects and its abdominal muscles wriggle in waves, so it can crawl forward slowly. At the same time, it can secrete a kind of mucus to help it crawl. When snails crawl, this mucus can protect their feet from damage.
It turned out that this sticky thing protected the snail when it climbed over the blade. Otherwise, it would have been "chopped into pieces". Nature is amazing!
5. Post "Steamed"
In hot summer, the heat is pressing, so it's very comfortable to eat a popsicle! Have you noticed that popsicles often steam when they are taken out of the refrigerator? Very interesting. Usually only hot things steam. Why do popsicles steam?
The temperature in summer is much higher than that of popsicles. Popsicle will melt when it meets air, and when it melts, it will absorb a lot of heat from the surrounding air, so the temperature of the air will drop. Usually the air contains a certain amount of water vapor, which is saturated or supersaturated due to the sudden drop of temperature. In other words, the air around the popsicle can't hold as much water vapor as it used to because of the temperature drop. In this case, the excess water vapor will form tiny water droplets and form a floating water droplet cloud, which will turn into white water vapor after being irradiated by light.
So do clouds, fog, rain and snow. The water in rivers, lakes and seas, after being irradiated by sunlight, constantly turns into steam and floats in the air. Air containing water vapor is heated and rises to a certain height. A cloud that condenses into suspended water droplets when it meets cold air is called a cloud. When the weather is cold, the water vapor near the ground can form a cloud of suspended water droplets. This is fog. So clouds and fog are essentially the same. Under the right conditions, the small water droplets in the cloud continue to merge into large water droplets until the rising airflow can't hold down, and then fall down to form rain. If it is winter, these water droplets will crystallize into snowflakes and fly all over the sky. However, the condensation of saturated water vapor in the air must have its condensation "core", that is, dust floating in the air, which is one of the necessary conditions to promote the formation of clouds, fog, rain and snow.
The secret of clouds greatly inspired the British physicist Wilson. After research, he invented a device called "Cloud Room" in 1894, which was filled with clean air and saturated vapor of alcohol (or ether). If you break into an invisible charged particle, it will become the core of "cloud" condensation and form fog spots, thus showing the "footprint" of particle movement. Therefore, scientists can observe the movements and changes of elementary particles (electron protons, etc.). ) invisible to the naked eye through the "cloud room". At the same time, many new elementary particles were discovered. Wilson's cloud room has made outstanding contributions to the study of the micro-world. 1927 won the nobel prize in physics.