1, Thales: measuring the pyramids skillfully. Thales saw that people were reading the notice, so he went to check it. The initial notice said that Pharaoh wanted the smartest person in the world to measure the height of the pyramid. So I went to Pharaoh. Pharaoh asked Thales what tools he used to measure the pyramids. Thales said he only used a stick and a ruler. He put the stick next to the pyramid. When the shadow of the stick was as long as the stick, he measured the length of the shadow of the pyramid and half the length of the bottom of the pyramid. Add these two lengths to get the height of the pyramid. Thales is really the smartest man in the world. He can easily measure the height of the pyramid without climbing to the top.

2. Horse racing in Tian Ji: During the Warring States Period, Qi Weiwang competed with general Tian Ji, and Qi Weiwang and Tian Ji each had three good horses: getting on, winning and dismounting. The race is divided into three times, and thousands of dollars are bet on each horse race. Because the horsepower of the two horses is almost the same, and Qi Weiwang's horse is better than Tian Ji's, most people think that Tian Ji will lose. However, Tian Ji took the advice of his disciple Sun Bin (a famous strategist) and dismounted Qi Weiwang, Ma Zhong of Qi Weiwang and Qi Weiwang. As a result, Tian Ji beat Qi Weiwang 2-/kloc-0-and got a daughter. This is an example of China's ancient substitution game theory to solve problems.

The story of Archimedes: 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 could not 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. When Archimedes saw this phenomenon, the lightning flashed 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.