煤和石油在利用过程中将产生严重的环境污染，而且在地球上储量有_爱下问搜题

搜题请搜索小程序“爱下问搜题”

问题填空题

煤和石油在利用过程中将产生严重的环境污染，而且在地球上储量有限，有朝一日将要被开采完毕，因此，寻找新的能源是人类努力的方向．利用风能发电就是一条开发新能源的途径，我国已建立了一定规模的风能发电站，假定某地强风的风速约为υ=20m/s，设空气的密度为ρ=1.3kg/m³，如果把通过横截面积S=20m²的风的动能全部转化为电能，则利用上述已知的量计算电功率时，其表达式为 P=______（用字母表示），计算结果大小为______w．

答案

风的动能Ekm=

1

2

mv2=

1

2

ρvtSv2=

1

2

ρv3tS．

则电功率P=

W

t

=

1

2

ρv3tS

t

=

1

2

ρv3S．

代入数据解得P=

1

2

×1.3×203×20W=1.04×105W．

故答案为：

1

2

ρv3S，1.04×10⁵．

填空题

词形转换：用括号内所给词的正确形式填空。

1. I am (real) happy to tell you about my future plans.

2. I think (dive) is the most dangerous activity.

3. Parrot has quite a (music) voice.

4. He sits in the front of the class because of his poor (eye).

5. Millie is clever, and she can always answer the questions (correct).

6. Millie has big (smile) eyes.

7. Yesterday he (give) his seat to an old woman on the bus.

8. What about (go) shopping?

9. The heavy rain stopped us from _______ (go) on a trip.

10. He jumped into the water when he heard a boy (call) for help.

多项选择题

部冒顶的处理方法主要有（）。

A.插楔法

B.木垛法

C.堵塞法