题目

When Stephen Hawking published A Brief History of Time in 1989, the reactions of the public were quite different from those of scientific circles. People who were not scientists described the book as a masterpiece. They said the book helped them understand what a very complex world astrophysics was. But scientists responded differently. They claimed the book was not scientific enough and relied too much on guessing, rather than on solid facts. Despite these conflicting views, the book has been wildly popular. Since its release in 1989, over 5.5 million copies have been sold with transl哈尔滨市方正县是松花江流域风能资源丰富地区，如图所示是该地区风力发电场的外景，下表给出了在不同风速下一台风车获得的能量．平均风速（m/s）510152025301s内获得的能量（×106J）24681012（1）若风速为10m/s，一台风车工作1h所产生的电能可供1千只“220V 100W”灯泡正常工作8h，求该风车发电的效率；（2）若该地区年平均风速为15m/s，50台这样的风车一年获得的风能相当于完全燃烧多少千克煤？（一年工作时间按4000h计算，煤的热值为3×107J/kg）；（3）根据题中获得的信息，分析风力发电的优缺点．（各写一条即可）