China Naming Network - Weather knowledge - Wind problem According to the observation of the meteorological department, there is a typhoon center at B, 240km due south of a certain coastal city A, with a central wind force of level 12.

Wind problem According to the observation of the meteorological department, there is a typhoon center at B, 240km due south of a certain coastal city A, with a central wind force of level 12.

Solution: 1. According to the meaning of the question, we know that the city will not be affected when reaching level 4, and the wind force at the center of the typhoon remains unchanged. Let us calculate the shortest distance from A to BC, as shown in the figure: AD=AB× sin30=240×1/2=120 kilometers. If it is not affected by the typhoon, then the city should be more than 25×(12-4)=200 kilometers away from the typhoon center. Because 200>120, it is affected by the typhoon

< p>2. As shown in the figure, the distance affected by the typhoon is EF, where AE=200 kilometers, AF=200 kilometers

Pythagorean theorem, DE=160 kilometers, so EF=2DE=320 Kilometers, duration=320/20=16 hours

3. The maximum wind force is when the typhoon moves to D, so the maximum wind force is 120/25=level 4.8