Archimedes' third famous saying - "Don't touch my circle!" In Archimedes' later years, the Roman army invaded Syracuse. Archimedes guided his compatriots to create many attacks and defenses. arms. When Marcellus, the leader of the invading army, led his troops to attack the city, he was repulsed by the "trebuchet" designed by Archimedes; the iron claw crane he built lifted the enemy ships and turned them upside down...Roman soldiers were frequently here Already frightened by the blow, as soon as they saw ropes or logs thrown from the city, they exclaimed "Archimedes is coming" and ran away with their heads in their hands. The Roman invading army was held back outside the city for three years. Finally, in 212 BC, the Roman invading army took advantage of the slight laxity in the defense of the ancient city of Syracuse and launched a massive attack into the city. At this time, the 75-year-old Archimedes was studying profound mathematical problems at home and drew a "unit circle" on the sand table... Brutal Roman soldiers broke in and trampled on the circle he drew. Archimedes He shouted angrily: "Don't touch my circle!" The ignorant Roman soldier waved his dagger, and the brilliant scientific superstar fell. Since then, "Don't touch my circle!" has become a mantra for scientists and engineers from all over the world to protect their rights to engage in scientific and technological creations... Archimedes' second famous saying - "Give me a fulcrum" , can move the earth!" Archimedes was not only a theorist, but also a practitioner. He is keen on applying scientific discoveries (principles) to technological inventions and practices (engineering), thereby combining scientific principles and technical engineering. Around 1500 BC, people in Egypt used levers (帋勋) to lift heavy objects, but they did not know its scientific principles, so they could not be promoted or used in other engineering constructions. Archimedes studied this phenomenon with great concentration and discovered the "lever principle". At that time, Syracuse built a large ship for the king of Egypt. It was huge and extremely heavy, but it could not be launched into the water, so it was stranded on the coast for a long time. Archimedes designed a complex system of levers and pulleys, installed them on the ship, and handed one end of the rope to King Hernon. King Hernon pulled the rope and a miracle happened! The big ship moved slowly and finally descended into the sea. In the king's great admiration, Archimedes smiled and said: "Give me a fulcrum, and I can push the earth." This famous saying not only explains the "leverage principle", but also has profound meaning, that is: as long as According to some conditions provided by science, corresponding technological inventions can be made and miracles can be created! So, for example, scientists and engineers in the United States often quote this famous saying when they are working on the development of missiles, satellites, and spacecraft. Archimedes' first famous saying - "Eureka! Eureka!" (Greek Eureka, meaning "I found it!") About Archimedes, there is such an interesting story: King of Syracuse let The craftsman made a pure gold crown for him. After it was completed, the king suspected that the craftsman had mixed silver into the gold crown. However, the gold crown was indeed as heavy as the pure gold that was originally given to the goldsmith. Did the craftsman do something wrong? Wanting to test the authenticity without destroying the crown, this problem not only stumped the king, but also made the ministers look at each other. So the king asked the scientist Archimedes to examine it. At first, Archimedes also thought hard but couldn't figure it out. One day, when he entered the bathtub to take a bath, the water overflowed out of the basin, and he realized a basic principle (the law of buoyancy): the weight of an object reduced in a liquid (buoyancy) is equal to the weight of the liquid displaced! ——Although objects of different materials have the same weight, due to different volumes, the water displaced will also be different. Based on this principle, we can determine whether the crown is adulterated. Archimedes jumped up with joy and ran home naked, shouting: "Eureka! Eureka!" (Greek Eureka, meaning "I found it!") He described this hydrostatic theory The basic principle was written into the famous book "On Floating Bodies" and is known to the world as "Archimedes' Principle", which is still included in physics textbooks. Many great scientists and mathematicians in later generations, when they made major discoveries, almost couldn't help shouting: "Eureka! Eureka!" - "I found it!"