Travel problem is a very common and easy to test application problem. Teacher Xu Li will analyze the clock problem in the travel questions, and there will be examples to explain and analyze different types of problems, so as to provide targeted learning and consolidation for everyone. I believe everyone will overcome the travel problem!

Knowledge points:

The problem of a clock is to study the relationship between the hour hand and the minute hand on the clock face, which can be regarded as a special problem of two people chasing or meeting on a circular track, but the two "people" here are the minute hand and the hour hand of the clock respectively.

On the clock face, every hand rotates clockwise, but because of the different speeds, the minute hand always catches up with the hour hand, or the minute hand exceeds the hour hand, so the common clock face problem is often transformed into the problem of catching up.

There are two common clock problems: (1) Study the problem that the hour hand and the minute hand form a certain angle, including coincidence, straight line, right angle or a certain angle; ⑵ Study the problem of time error, that is, the speed of the clock.

The clock problem is different from other travel problems because the measurement of its speed and total distance is no longer one meter per second or one kilometer per hour, but "how many angles are taken per minute" or "how many squares are taken per minute" by two hands. For a normal clock, specifically: the whole clock face is 360 degrees, and there are 12 squares on it, each square is 30 degrees; 60 squares, 6 degrees each.

Minute speed: per minute 1 grid, 6 degrees per minute.

Clockwise speed: per minute112, per minute 1/2=0.5 degrees.

Note: However, in many clock problems, we often encounter all kinds of "strange clocks" or "bad clocks", whose hour hand and minute hand move at different angles per minute from conventional clocks, which requires us to learn to analyze different problems independently.

We should regard the clock problem as a stroke problem, because the minute hand is fast and the hour hand is slow, so the problem between the minute hand and the hour hand is the problem of catching up between them.

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