问题 计算题

(10分)我国继“神舟”八号载人飞船成功发射后,又准备在今年6月择机发射“神舟”九号载人飞船。把“神舟”九号载人飞船在一段时间内的运动看成绕地球做匀速圆周运动,宇航员测得自己绕地球做匀速圆周运动的周期为T、距地面的高度为H,已知地球半径为R,引力常量为G。求:

(1)地球的质量;

(2)飞船的向心加速度大小。

答案

(1)(2)

(1)设地球的质量为M。=   (4分)

解得:M =                                       (2分)

(2)飞船的向心加速度大小:a= 

本题考查万有引力定律的应用,公式中半径为卫星距离地球球心间的距离,及R+H,由此可求得地球质量,向心加速度公式a=

单项选择题
阅读理解

阅读理解。

      George Banks was a clever journalist. He worked for a good newspaper, and  he liked arguing

very  much. He argued with anybody, and about anything. Sometimes the people whom he argued

with were as clever as he was, but often they were not.

      He did not mind arguing with stupid people at all: he knew that he could never persuade them to

agree, because they could never really understand what he was saying, and the stupider they were,

the surer they were that they were right; but he often found that stupid people said very amusing things.

     At the end of one argument which George had with one of these less clever people, the man said

some-thing which George has always remembered and which has always amused him. It was, "Well,

Sir, you should never forget this: there are always three answers to every question: you answer, my

answer,and the  correct answer."

1. It seemed to George as if ________.

A. it was more interesting to argue with as clever people as he was

B. it was more interesting to argue with clever people than with stupid ones

C. it was more interesting to argue with stupid people than with clever ones

D. it was no good arguing with stupid people

2. From the passage we can conclude that________.

A. George did nothing but argue with others

B. George was a man full of sense of humour

C. George always won the arguments

D. What George said was difficult to understand

3. Why didn't George mind arguing with stupid people? Because ________

A. he wanted to win the arguments

B. he wanted to make the arguments more heated

C. stupid people could be easily fooled

D. what stupid people said could often give him greater pleasure

4. What one of the stupid people said at the end of one argument could be considered very________.

A. clever

B. stupid

C. strange

D. special