(20 12? During May Day in Luzhou, Xiaoming and his classmates went to the playground. The picture shows the schematic diagram of a large ferris wheel in an amusement park, with a radius.

Solution: (1) Let Xiao Ming arrive at point C after 4 minutes, and pass the CD⊥OB with point C as point D, and DA is the height of Xiao Ming from the ground.

∫∠COD = 36024×4 = 60，

∴od= 12oc= 12×20= 10，

∴da=20- 10+ 1= 1 1(m).

Answer: After 4 minutes, Xiaoming's height from the ground is11m.

(2)∵ When rotating to E, make the extension line OF the chord EF⊥AO from H point to AO point, and connect o E, of. At this time, the height of EF from the ground is ha.

When HA=3 1 and OH = 31-kloc-0/-20 =10,

∴OH= 12OE，

∴∠HOE=60，

∴∠FOE= 120。

∫ The rotation angle per minute is: 36024 = 15,

∴ The time required to rotate from point E to point F is: 120 15=8 (minutes).

A: Every time Xiaoming makes a turn, he will stay in the air above 3 1m for 8 minutes.