There are 60 squares on the clock. When the minute hand completes 60 squares, the hour hand completes 5 squares. It can be understood that the running speed of the minute hand is 12 times that of the hour hand. When the minute hand is perpendicular to the hour hand, it happens when the difference between the two hands is 15 square; Between 4 o'clock and 5 o'clock, there are two situations where the minute hand is vertical, one is that the minute hand is in front of the hour hand, and the other is that the minute hand is behind the hour hand, but the distance between the two hands must be 15;
Then this topic can be equivalent to: the minute hand is at point A, the hour hand is at point B, the distance between point A and point B is 20 meters, and the speed of the hour hand is 5 meters per hour; The minute hand travels at a speed of 60m/h, and the two hands travel in the same direction. How long does it take, the distance between two stitches 15m? Then suppose that after x hours, the distance between the two needles is15m; So we can get two cases: 20+5x-60x= 15, or 60x-(20+5x)= 15. Find the value of x and finally get: x =111hour and X = 7/65438. Even if converted into seconds, this result cannot be divided, that is, 3600/1 is about 5 minutes and 27 seconds, 3600*7/ 1 1 is about 38 minutes1second;
As can be seen from the above, between 4 o'clock and 5 o'clock, the vertical time of the minute hand and the hour hand is 4: 05: 27 and 4: 38: 1 1 second respectively!
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