A 500-word scientific paper
At first, people used the principle of air and tried their best to create this remarkable first one? A flying bird? Hot air balloon. But when the storm came, there was nothing I could do but watch it fall from the sky. Although the hot air balloon has realized people's wishes, it is not perfect. Later, the Wright brothers in America made the first airplane in history. This feat made the human dream of flying come true. Since man made the first plane himself, he has improved the plane again and again, making the dream of flying perfect. But mankind is not satisfied with just flying in the sky, but decided to explore the mysteries of the universe.
In 2000, mankind made great progress. They have sent their spacecraft into the sky many times to explore other planets. Although we have made the spaceship a guest in space, we still haven't realized the dream of manned space flight. Scientists in China are busy realizing this wish. Finally, in September 2004? SHEN WOO? Uncle Yang Liwei, a space hero, successfully launched and returned safely with the hope of the people of the whole country.
? SHEN WOO? After the launch, Shenzhou VI? Fly into space. ? Shenzhou VI? This launch excited me, an ordinary pupil. I believe. Seven gods Ba Shen? The launch will not be too far away, and they will also leave a brilliant mark on China's space history. Let's fly to the ocean of knowledge with a heart that looks forward to flying like a bird, work hard and make contributions to the future of our motherland!
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Scientific 500-word essay II
When the weekend came, my mother asked me to shine my shoes at home, and I readily agreed. I went to the shoe cabinet and looked at these dusty shoes. I have been polishing them. Suddenly, a question flashed through my mind. Why are leather shoes getting brighter and brighter?
Experiment: I found two pairs of old and new leather shoes of the same brand and style for comparative observation. I first touched the uppers of two pairs of leather shoes and found that the surface of the new shoes was much smoother than the old ones. Old leather shoes are coated with shoe polish. After careful polishing, it shines a lot, but it is still not as good as new leather shoes. Is there a relationship between the brightness of leather shoes and the smoothness of uppers?
I brought a pair of old leather shoes that were not polished, and the uppers were uneven under the magnifying glass. Then, I carefully wiped one shoe with shoe polish, and the other shoe without shoe polish was used as a blank control. I found that after the first piece was wiped, the surface became much smoother and brighter than the other piece in the sun. Why is there such a big difference between them?
Answer: I searched online and learned that the surface of leather shoes is not absolutely smooth. If it is an old leather shoe, its surface is of course more uneven and can't be reflected in a certain direction, so it looks dull. There are some small particles in shoe polish, which can just be filled into the pits on the surface of leather shoes when shining shoes. If you wipe it with a cloth again to make the shoe polish more uniform, the surface of leather shoes will become smoother and smoother, and the reflective ability will be strengthened.
I finally know why shoes are getting brighter and brighter. In the initial life? Question mark? Quite a lot!
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Scientific 500-word essay III
Today, when I was watching TV at home, I suddenly thought of a question: Why do cartoon characters, backgrounds and other things in TV change with time?
I first made a guess: if there is a big disk in the TV structure, all the pictures are fixed on this big disk, because the relationship between this disk and the antenna on the remote controller is like two magnets that can attract each other, so the remote controller can control the TV easily. I also did a small experiment in the classroom. I wrote one, two, three, four, five, six, seven, eight, nine and ten on a long piece of paper. I put the pen in the middle space, and I turned it slowly, and the numbers on it also turned slowly in front of my eyes. I don't turn, and the numbers on it don't turn. I quickly turned the pen, and the numbers on it also turned quickly.
Now, my hand is like a remote control, controlling the speed and channel of TV, and the pen in the middle is like an antenna, passing what I control and passing what I control in? Television? Small notes with numbers written on them are like TV. I press the remote control to fast forward, and the program on TV will be finished soon. At this moment, I understand that the TV we see is tied up with some designed pictures and movies. In order to prove my point, I found the book "100,000 Why Live", which said that comics were born in 183 1. The Frenchman Prato put the painted pictures on the disc of a machine with an observation window in sequence, and the pictures rotate with the disc to form a moving picture, which is the original prototype of the cartoon. After that, there were four transformations, namely: 1906 Stewart in the United States, 1908 Cole in France, and 1909 Cole in the United States. 19 15 Hurd, USA, and finally from 1928, Walter Disney improved the animation system and production technology, and linked the production of cartoons with commercial value, pushing cartoons to the peak.
I think students who love painting can try to draw a few pictures by themselves, nail them together and turn pages quickly, which will have the same nature as comics.
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Scientific 500-word essay IV
Learning and living can't be separated from paper, and the raw material of paper making is mainly the fiber of plants such as bark, but because people cut it blindly. There are fewer and fewer trees now, so we should save paper. It is everyone's responsibility to start from the little things around us.
? Save paper? For us, it seems a little far away compared with saving water and electricity. Few people know the direct relationship between saving paper and protecting the ecological environment. Each of us uses paper every day, using different types of paper. Have you counted them? How many sheets of paper do you use every day? How much paper do you need a week? How many sheets of paper do you need from one month to one year? The result is amazing. Where does a piece of paper come from? Is paper made of trees? Change? Here it is. It often takes decades for a tree to be used by human beings. Human beings are heartless. With the sound of a chainsaw, the tree that had grown for decades fell to the ground. Wood was transported to the paper mill and turned into pieces of paper. Paper has brought convenience to human beings, but at the same time it has also brought great influence to forests. Trees can not only be used to make paper, but also provide wood. A large area of forest can conserve water, prevent soil erosion and purify the air. If there are no trees, there will be no oxygen, and then we will have no place to live. The harm of forest disappearance is great: the Loess Plateau was originally a forest, lush and endless, with green waves rippling. However, due to the destruction of people, the Loess Plateau has really become a plateau with only loess, and the earth has taken off its coat and exposed its yellow skin, which is so sad.
What is March 12 every year? Arbor Day? . On this day, we all take tools to plant trees. Now the forest coverage in China has increased. This is the result of human introspection, which is gratifying.
However, although the forest coverage rate has increased, it is still very low. Therefore, afforestation is an arduous task and an eternal task for mankind. It's winter now, although it's past the best time to plant trees, but we can spread it in our hearts? Save paper? Seeds, planting? Planting trees? By the next spring, these trees will sprout and grow tall. We can go outdoors with tools, sow the seeds of trees on the earth, take good care of them and make the motherland full of green! Protect us from wind and rain. Save paper, start with me.