Title: Station A is located in the upper reaches of the river, and Station B is located in the lower reaches of the river. Ship A comes from Station A, and ship B comes from Station B, in opposite directions. Since 65438+February, the two ships have new engines, and the speed has become 1.5 times of the original. At this time, the meeting place has been changed to1000m, 65438+February 6th.

Answer:

First of all, because the downstream is ship speed+water speed, the upstream is ship speed-water speed. The speed of water increases and decreases, which cancel each other out.

So the time when the two ships meet is only related to the speed of the ship, not to the speed of the water.

Then, when the ship speed becomes 1.5 times on February 2, the time spent will become 2/3 of the original time.

At this time, if water is not considered, the actual distance that the nail travels downstream should remain unchanged, because the speed becomes 1.5 times.

Now, because of the downstream, we have to consider the speed of water. That is to say, the 1000m of the site movement is 1/3 of the original water time.

The distance traveled inside.

Then the speed of water will be twice as fast as before, and this situation is still the same sentence. Time is only related to the speed of the ship, not to the speed of the water, so the total time is still 2/3 of the initial time, and then the movement of the meeting point will be analyzed according to the above method:

The speed of A is the speed of the ship+the speed of the water. Time is constant, so is the speed of the ship, so the movement of the intersection is only related to the speed of the water. This time, the speed of water has doubled, and the time is still 2/3 of the initial time. We also analyzed that the distance traveled by water in the initial time of 1/3 was 1000 meters, so this time the intersection moved (2/3)/(1/3) *1000 = 2000.

Mathematics (hanyu pinyin: shùXué；; ; Greek: μ α θ η μ α κ; English: Mathematics comes from the ancient Greek word μ θ η μ α (má th?ma), which means learning, learning and science. Ancient Greek scholars regarded it as the starting point of philosophy and the "foundation of learning". In addition, there is a narrow and technical meaning-"mathematical research". Even in its etymology, its adjective meaning related to learning will be used to refer to mathematics.

Its plural form in English and as the plural form of mathématiques in French +es can be traced back to the Latin neutral plural (Mathematica), which is Cicero's plural from Greek τ α α θ ι α τ κ? (ta mathēmatiká)。

In ancient China, mathematics was called arithmetic, also called arithmetic, and was finally changed to mathematics. Arithmetic in ancient China was one of the six arts (called "number" in the six arts).

Mathematics originated from early human production activities. The ancient Babylonians had accumulated some mathematical knowledge, which could be applied to practical problems. Judging from mathematics itself, their mathematical knowledge is only obtained through observation and experience, and there is no comprehensive conclusion and proof. However, we should fully affirm their contribution to mathematics.

The knowledge and application of basic mathematics is an indispensable part of individual and group life. The refinement of its basic concepts can be seen in ancient mathematical classics of ancient Egypt, Mesopotamia and ancient India. Since then, its development has made small progress. But algebra and geometry at that time were still independent for a long time.

Algebra can be said to be the most widely accepted "mathematics". It can be said that algebra is the first mathematics that everyone has come into contact with since childhood. Algebra, as a discipline to study numbers, is also one of the most important parts of mathematics. Geometry is the earliest branch of mathematics studied by people.

Until the Renaissance in16th century, Descartes founded analytic geometry, which linked algebra and geometry which were completely separated at that time. From then on, we can finally prove the theorem of geometry by calculation. At the same time, abstract algebraic equations can be expressed graphically, and later more subtle calculus was developed.

There are many branches of mathematics at present. French Bourbaki School, founded in 1930s, thinks that mathematics, at least pure mathematics, is a theory to study abstract structures. Structure is a deductive system based on initial concepts and axioms. They think that mathematics has three basic parent structures: algebraic structure (group, ring, field, lattice …) and ordered structure (partial order, total order …).

Mathematics is applied in many different fields, including science, engineering, medicine and economics. The application of mathematics in these fields is generally called applied mathematics, which sometimes arouses new mathematical discoveries and promotes the development of a brand-new mathematics discipline. Mathematicians also study pure mathematics, that is, mathematics itself, without any practical application. Although many works begin with the study of pure mathematics, they may find suitable applications later.

Specifically, there are sub-fields to explore the relationship between the core of mathematics and other fields: from logic and set theory (mathematical basis), to empirical mathematics in different sciences (applied mathematics), to more modern uncertainty research (chaos and fuzzy mathematics).