(1) Determination of Archimedes' lever principle: People have been using levers since ancient times and know how to use them skillfully. When the pyramids were built in Egypt, slaves used levers to pry up heavy stones. The shipbuilder used a lever to erect a mast on the ship. People use shaduf to get water from wells and so on. But why can leverage do this? No one could explain the lever law before Archimedes discovered it.
At that time, when talking about this issue, some philosophers insisted that it was "magic". Archimedes denied what "magic" it was. He knows that there are always natural reasons for all kinds of phenomena in nature. Lever also has its natural reasons, and he is determined to explain it. After repeated observation, experiment and calculation, Archimedes finally established the law of lever balance. That is, "the arm of force is inversely proportional to the force (weight)." In other words, it is: how many times is the small weight and how many times should the long arm be the short arm.
After Archimedes established the lever law, he concluded that any heavy object can be lifted with little force as long as the appropriate lever length can be obtained.
It is said that he once said such grandiloquence: "Give me a fulcrum and I will lift the earth!" " "King Syracuse heard this and said to Archimedes:" In the name of Zeus (Zeus is the king of the gods in Greek mythology, in charge of heaven, thunder, electricity and rain), what you said is really strange, Archimedes! "After Archimedes explained the characteristics of lever to the king, the king said," Where can I find a fulcrum to lift the earth? ""there is no such fulcrum. " Archimedes replied, so, it is impossible to make people believe in the power of mechanics? "The king said no, no, you misunderstood, your majesty. I can give you other examples. "Archimedes said. The king said, "You are too boastful! You can help me push the same weight, see what you say. "
At that time, the king had a problem, which was to build a very big ship for the king of Egypt. After the ship was built, the whole city of Syracuse was mobilized, and it was impossible to push it into the water. Archimedes said, "Well, I'll push the boat for you." After Archimedes left the king, he used the principle of lever and pulley to design and manufacture a set of exquisite machinery. When everything was ready, Archimedes invited the king to watch the ship launch. He gave the end of a thick rope to the king to pull gently. Suddenly, the big ship moved slowly and slipped into the water smoothly. When the king and ministers saw such a miracle, they were as surprised as if they were watching magic! So the king persuaded Archimedes and issued a notice to the whole country: "From now on, no matter what Archimedes says, we must firmly believe him ..."
(2) Archimedes principle: In the eyes of ordinary people, Archimedes is a "freak". In the words of Plutarch, a Roman historian, "He seems to be an enchanted man. He doesn't care about food or his body." Sometimes, the rice is put on the table and asked to eat, but he doesn't seem to hear it. He is still drawing his geometry in the ashes of the brazier. His wife should look after him at all times. For example, when he rubbed his body with oil, he just sat and oiled himself and forgot what he had done. His wife is more afraid of sending him to the bathhouse to take a bath. The joke was caused by the crown of a new king.
Not long ago, the king asked a craftsman to build him a golden crown. The king gave the craftsman the gold he needed. The craftsman's craft is very clever, and the crown produced is exquisite and unique, and the weight is as heavy as the gold given by the king at the beginning. However, someone reported to the king: "When making the crown, the craftsman swallowed some gold privately and mixed the same weight of silver." Hearing this, the king became suspicious, so he called Archimedes and asked him to try to determine whether the gold crown was mixed with silver and whether the craftsmen kept the gold for themselves.
Archimedes was stumped this time. When he got home, he thought hard for a long time and couldn't find a way. I can't eat, sleep or take a shower every day, as if I were possessed. One day, the king sent someone to urge him to report to the palace. His wife saw that he was too dirty and forced him to take a bath. When he was taking a bath in the bathhouse, he was still thinking about weighing the crown. Suddenly, he noticed that some water overflowed from the side of the bathtub when his body sank into it. At the same time, he felt that the deeper he went into the water, the lighter he was.
So, he immediately jumped out of the bathtub, forgot to wear clothes and ran to the street of the crowd. He ran and shouted, "I found it, I found it, and the solution to the crown was found!" " After he entered the palace, he said to the king, "Please allow me to do an experiment and then report the result to you." The king agreed. Archimedes put the gold, a piece of silver and the crown, which are as heavy as the crown, in the basin one by one, and saw that the gold nugget discharged less water than the silver nugget, while the crown discharged more water than the gold nugget. Archimedes said to the king, "The crown is mixed with silver!" " "The king saw the experiment and didn't understand. Let Archimedes explain.
Archimedes said, "One kilogram of iron is bigger than one kilogram of wood. If you put them in water separately, the big wood will discharge more water than the small iron. I apply this principle to gold, silver and crowns. Because the density of gold is high and the density of silver is low, the volume of silver must be greater than that of gold when gold and silver are equally heavy. Therefore, when gold nuggets and silver nuggets with the same weight are put into water, the amount of water discharged by gold nuggets is less than that of silver nuggets. The experiment just now proves that the crown discharges more water than the gold nugget, indicating that the density of the crown is smaller than that of the gold nugget, which proves that the crown is not made of pure gold. "
Archimedes' methodical narration persuaded the king. The experimental results prove that the craftsman put the gold in his pocket. This experiment of Archimedes is the embryonic form of "hydrostatics". However, he did not stop there and continued to study the floating body problem in depth. Results Archimedes principle, an important principle in natural science, was discovered. That is, when an object is immersed in a liquid, the volume of the displaced liquid is equal to the volume in which the object is immersed; Keep the buoyancy of the floating body equal to the weight of the liquid discharged by the floating body.
The king made a golden crown. He suspected that the craftsman had stolen some gold with silver, so he asked Archimedes to identify whether it was made of pure gold and not to damage the crown. Archimedes thought hard about the crown all day. One day, Archimedes went to the bathroom to take a bath. He went into the bath tub. When he immersed himself in the bath bucket, some water overflowed from the side of the bucket. Archimedes saw this phenomenon and crackled in his mind. "I found it!" . Archimedes put an equal weight gold nugget and a silver nugget into a container filled with water, and found that the silver nugget discharged much more water.
So Archimedes took a gold nugget with the same weight as the crown and put it in a container filled with water to measure the displacement; Then put the crown in a container filled with water to see if the amount of water discharged is the same, and the problem will be solved. With further research, Archimedes principle, the most important cornerstone of fluid mechanics, was born.
In addition, he burned the enemy warships with a mirror. Before he was killed, he made the enemy wait and let him finish a math problem. Birthday greetings from colleagues, 2 190 years ago, a great physicist appeared in Syracuse, Sicily, ancient Greece. His name is Archimedes (287-2 BC12 BC).
Archimedes studied hard all his life, devoted himself wholeheartedly to science and was loyal to the motherland, and was respected and praised by people. Archimedes discovered the lever law and Archimedes principle named after him. And use these laws to design all kinds of machinery to serve the people and the motherland. The details of his life cannot be confirmed. But the story about his invention and defense of the motherland has been passed down to this day.
(3) Discovery of buoyancy principle: It is said that once Hilong II made a gold crown, but he always suspected that the goldsmith stole his gold and mixed silver in Wang Guanzhong. So he asked Archimedes to identify it, provided that the crown was not damaged. At that time, people didn't know that different substances had different proportions. Archimedes thought hard for many days, and there was no good way. One day, he went to take a bath. Hardly had he got into the tub filled with warm water when the water overflowed and he felt his body floating slightly.
So it suddenly occurred to him that the same weight of objects, due to different volumes, discharged different amounts of water ... He stopped taking a shower, jumped out of the bathtub and ran home naked from the street. When his servant came home panting, Archimedes was already doing experiments; He put the crown in a basin full of water, measured the overflowing water, and put the same weight of pure gold in the basin full of water, but the overflowing water was less than before, so he concluded that the goldsmith had mixed silver in Wang Guanzhong. From this, he discovered the principle of buoyancy and recorded it in the famous book "On Floating Bodies", which is called Archimedes Principle today.
(4) The Battle of Syracuse: Archimedes: The Battle of Syracuse In Archimedes' later years, Roman troops invaded Syracuse, and Archimedes instructed his compatriots to make many combat weapons for attack and defense. When Marcelle Sai, the leader of the invading army, led a group of people to attack the city, he designed a trebuchet to beat the enemy out of the water.
His iron claw crane can lift enemy ships and turn them upside down ... Another incredible legend is that he led the people of Syracuse to hold concave mirror, focused the sunlight on the wooden warships of the Roman army and set them on fire. Roman soldiers have been frightened by such frequent blows. They are afraid of everything. As soon as they saw the rope or wood thrown from the city, they exclaimed "Archimedes is coming" and then ran around.
Roman troops were kept out of the city for three years. Finally, in 2 12 BC, the Romans took advantage of the slight relaxation of the defense of the ancient city of Sila to attack on a large scale. At this time, 75-year-old Archimedes was studying an abstruse math problem. A Roman soldier broke in and trampled on his painting with his foot. Archimedes argued with him angrily. The cruel and ignorant soldier raised his knife and a talented science superstar fell.