From 65438 to 0666, 23-year-old Newton was a junior at Trinity College, Cambridge University. Seeing his fair skin and long blond hair, many people thought he was still a child. He is thin, taciturn and serious, which makes people believe that he is still a child. His sharp eyes and angry expression all day make people stay away from him.
The Black Death swept through London and claimed many lives. This is really a bad day. The university was forced to close, and people who are keen on learning like isaac newton had to return to the safe countryside, expecting the disease that swept the city to leave as soon as possible.
In the countryside, Newton was always troubled by such a question: what drives the moon to go around the earth and the earth to go around the sun? Why won't the moon fall to the earth? Why doesn't the earth fall to the sun?
In the following years, Newton claimed that this happened. Sitting in his sister's orchard, Newton heard a familiar voice, and an apple fell on the grass with a bang. He turned quickly to watch the second apple fall to the ground. The second apple fell from the outstretched branch, bounced on the ground and lay quietly on the grass.
This apple is definitely not the first apple Newton saw fall to the ground. Of course, the second apple is no different from the first one. Although the apple landing did not provide Newton with an answer, it inspired the young scientist to think about a new problem: the apple will land, but the moon will not. What's the difference between an apple and the moon?
The next morning, it was sunny, and Newton saw his little nephew playing with a ball. He has a rubber band tied to his hand, and a ball tied to the other end of the rubber band. He swung the ball slowly first, then faster and faster, and finally the ball was thrown straight.
Newton suddenly realized that the movements of the moon and the ball were very similar. There are two forces acting on the ball, one is the outward driving force, and the other is the tension of the rubber band. Similarly, there are two forces acting on the moon, namely, the driving force of the moon's movement and the pulling force of gravity. It is under the action of gravity that the apple will fall to the ground.
Newton believed for the first time that gravity is not only a force between planets and stars, but also a universal force. He believed in alchemy and thought that matter attracted each other, which led him to assert that mutual attraction applied not only to huge celestial bodies, but also to objects of various sizes. Apples fall, raindrops fall, and planets revolve around the sun, all of which are the results of gravity.
2. Luban invented the "saw"
The story of Lu Ban inventing the saw has been circulated among the people for thousands of years. Legend has it that one year, Luban accepted the task of building a huge palace. The palace needed a lot of wood, so Lu Ban sent his disciples up the mountain to cut down trees. Since there was no saw at that time, his disciples had to use axes to cut, but the efficiency was very low. The craftsmen had to work hard every morning.
I'm exhausted. I can't cut down many trees, which is far from meeting the needs of the project. The progress of the project has been delayed again and again. Seeing that the project deadline is getting closer and closer, I am anxious for Luban. To this end, he decided to personally go up the mountain to see the situation of cutting trees. When going up the mountain, he accidentally caught a handful of weeds growing on the mountain, but suddenly cut his hand.
Lu Ban wants to know why a grass is so sharp. So he picked a leaf and observed it carefully. He found many small teeth on both sides of the leaf. These little teeth are very sharp when he touches it gently.
He knew that his hand had been cut by these small teeth. Later, Lu Ban saw a big locust eating leaves in a meadow. The two large molds are very sharp. As soon as they opened and closed, they quickly ate a big piece.
This also aroused Lu Ban's curiosity. He caught a locust and carefully observed the structure of its teeth. He found that locusts also had many small teeth on their two big dies, which were used by locusts to bite grass leaves. These two things left a deep impression on Lu Ban, and also gave him great inspiration. He fell into deep thinking.
He thought, if the tool for cutting wood is serrated, isn't it sharp? It will be much easier to cut down trees. So he made a bamboo with many small serrations from a big bamboo, and then went to a small tree to do experiments. The result is really good. After a few quick tugs, the bark was torn, and after a few more tugs, a deep ditch was made in the small tree stem. Luban is very happy.
However, bamboo can not be used for a long time because of its softness and poor strength. After pulling for a while, some small serrations are broken and some are dull, so it is necessary to replace bamboo.
This affects the speed of cutting down trees, and it is also a great waste to use too many bamboo chips. It seems that bamboo is not suitable for making sawtooth, so we should find a material with higher strength and hardness to replace it. At this time, Lu Ban thought of the iron sheet.
So they immediately went down the mountain, and the blacksmith helped to make small serrated iron pieces, and then went up the mountain to continue their practice. Lu Ban and his apprentice each pulled one end and pulled it up on a tree. I saw them coming and going, and soon I sawed off the tree, which was quick and labor-saving, and the saw was invented.
3. Zipper
Zipper was first invented by Chicago mechanic Judson in 189 1 year. In order to relieve the trouble of tying shoelaces every day, Judson invented a zipper which can replace shoelaces.
This zipper consists of a row of hooks and a row of buttonholes. Pull an iron slider from bottom to top, and the hook and buttonhole can be fastened one by one. Judson sent the sample to Columbia Expo on 1893, which was well received and patented.
4, Galileo's discovery
One day more than 300 years ago, Galileo went to worship in Pisa Cathedral. A chandelier hanging in the air in the church was swayed back and forth by the wind blowing around the door.
This caught his attention. "Strange, why does it take the same time every time?" Galileo raised such a question. In order to ensure the same swing time every time, he suddenly thought of using his own pulse test when he was studying medicine. "It's true!" ? Galileo was pleasantly surprised by his discovery.
Then he thought, "If the chandeliers are different in size. What's the difference in timing? What if the rope hanging the chandelier is long or short? " After returning home, Galileo began his experiment.
The results show that the swing speed has nothing to do with the weight of the object. When the line is long, it swings slowly, and when it is short, it swings fast. Later, people made clocks according to Galileo's discovery.
During World War II, the root pig mouth function invented the gas mask.
During the First World War, the Germans fought fiercely with the British and French allied forces for the Igor region of Belgium, and the two sides confronted each other for half a year. 19 15 years, in order to break the long-term deadlock in the European battlefield, the Germans used chemical agents for the first time.
They set up 5,730 steel cylinders filled with chlorine gas at the front of the position, opened the bottle caps of the downwind position of the British and French allied forces, and released 180 tons of gas.
Suddenly, a piece of green smoke rose and floated to the other position at a speed of three meters per second, spreading to the position where the allied forces jumped 25 kilometers. Results 50 thousand British and French soldiers died of poisoning, and a large number of wild animals on the battlefield were poisoned one after another.
But strangely, the wild boar in this area actually survived. This incident aroused great interest of scientists. After on-the-spot investigation and careful study, it was finally found that wild boars like to arch the ground with their mouths, which saved them from dying.
When the wild boar smells a strong pungent smell, it arches the ground with its mouth to avoid the stimulation of the smell. After the soil is arched by wild boar, its particles become soft, which plays a role in filtering and adsorbing toxic gases.
Because the wild boar skillfully used the gas mask given to it by nature, it was able to survive the chlorine disaster. According to this discovery, scientists quickly designed and manufactured the first batch of gas masks.
However, this kind of gas mask does not use soil as adsorbent directly, but uses activated carbon with strong adsorption ability, and the shape of pig mouth can hold more activated carbon. Although the performance of the adsorbent is getting better and better now, it looks like a pig's mouth, but it has not changed.