Most people often have a wrong understanding of sailing, thinking that sailing is driven by the wind. In fact, the biggest power source of sailboats is the so-called Bernoulli effect, that is, when air flows through an arc surface similar to a wing, it will produce a forward and upward gravity, which will make sailboats move in a certain angle against the wind. In sail before the wind, however, the Bernoulli effect disappears and ships cannot reach the maximum speed.
However, the sailing course is not completely unlimited. It is impossible to produce an effective forward force at an angle of about 45 degrees between positive and negative winds, but it is not good to be too downwind. At this time, the Bernoulli effect disappeared, the ship speed slowed down again and entered an unstable state. However, a ship with the ability to sail against the wind must take a tortuous route to reach its destination if it wants to sail against the wind.
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Bernoulli, discoverer of the principle of navigation;
Daniel bernoulli is the most outstanding of the famous Bernoulli family. He is the second son of johann bernoulli.
When Daniel was born, his father John was a professor of mathematics in Groningen. Daniel 17 13 began to study philosophy and logic, 17 15 got a bachelor's degree, and 17 16 got a master's degree in art. During this period, his father, especially his brother Nicolaus Bernoulli, taught him math for the second time, which made him influenced by his math family.
His father tried to get him to be a business apprentice and find a business career, but the idea failed. So he was asked to study medicine, first in Basel, 17 18 in Heidelberg, 17 19 in Strasbourg, and then he 1720 returned to Basel. 172 1 obtained the doctorate of medicine through thesis defense.
1723, Daniel went to Venice. 1724, he published Mathematical Practice in Venice, which attracted many people's attention and was invited to work in the Academy of Sciences in Petersburg. 1725, he returned to Basel. Later, together with my brother Nicholas II, I accepted the invitation of Petersburg Academy of Sciences to work in Petersburg Academy of Sciences.
During his eight years in Petersburg (1725— 1733), he was appointed as an academician of physiology and mathematics. 1727, he worked with L. Euler, who was Daniel's assistant at first, and later took over Daniel's position as an academician of mathematics. However, due to the sudden death of his brother Nicholas II and the bad weather, he returned to Basel on 1733.
He is a professor of anatomy and botany in Basel, a professor of physiology in 1743, a professor of physics in 1750 and a professor of philosophy in1777.
1733, after Daniel left Petersburg, he began the most acclaimed scientific exchange with Euler. In the communication, Daniel provided the most important scientific information for Euler, and Euler used his excellent analytical ability and rich work experience to give him the fastest help.
They corresponded for 40 years, and the most important communication was during 1734- 1750. They are the closest friends and competitors. Daniel also has academic contacts with mathematicians, such as C. Goldbach.
Baidu Encyclopedia-Bernoulli Effect