问题 问答题

如图,一颗子弹水平射入一原来静止的单摆摆球并留在摆球内,结果单摆开始做简谐运动,其振动图线如图所示。已知子弹的质量为m=10g,摆球质量M=10kg。那么根据力学规律和题中(包括图)提供的信息,对反映振动系统本身性质的物理量、子弹以及子弹和摆球一起运动过程中的守恒量,你能得到那些定量的结果?(g=10m/s2

答案

(1)摆长4m  (2)振动系统的总能量2J(3)子弹的初速度633m/s

从图中可以看出,单摆的周期T=4s;振幅A=40cm

(1)根据单摆的周期公式可求得摆长ll=4m

(2)振动系统的总能量EE=(m+M)gh=(m+M)g()=2J

(3)子弹的初速度v0    

代入数据解得,v0=633m/s

阅读理解

阅读理解。

     The first reality TV show in the world was called Expedition Robinson and it was shown in Sweden in

1997. Half the population of the country watched the final event and a new kind of TV program was born.

Two years later in Holland, the first series of Big Brother was filmed. Again, it was a great success and the

final program was watched by 15 million people. Now more than 20 countries around the world have Big

Brother or Expedition Robinson on their TV screens. The ordinary people who take part in the programs

are known by millions of people in their own countries and reality TV has become big, big business.

     For the TV producers, reality TV is a dream which come true because many of the programs cost nothing

to make. At some point, the television viewers (观众) are asked to telephone the program to vote or to apply

to take part in the show. It is the cost of these telephone calls that pays for the shows. One of the most

popular shows is Pop Idol. In the show, a group of attractive young people are made into pop stars. TV

viewers vote for their favorite person on the show. The winner makes a record and millions of copies of the

record are sold. His or her pictures are published on the covers of magazines or on the front pages of

newspapers, and then, they are quickly forgotten.

     But not everyone is happy about reality TV. In Portugal, two TV channels got into trouble because they

showed too much of the personal lives of the people in the shows. In France, reality TV is called "rubbish

TV" and the TV studios of Big Brother were attacked three times in one week. In Greece, Big Brother was

described as "against human rights and civilization".

1. Those who take part in reality TV shows are usually _____.

A. common people

B. pop TV Stars

C. attractive people

D. famous film stars

2. Who would pay for the cost of reality TV shows according to the passage?

A. TV producers who make reality TV shows.

B. TV actors who take part in reality TV shows.

C. TV viewers who telephone reality TV shows.

D. TV companies which broadcast reality TV shows.

3. Which of the following statements is NOT true according to the passage?

A. Pop Idol is one of the popular reality TV shows in the world.

B. Big Brother was one of the first reality TV shows in the world.

C. Rubbish TV is one of the personal reality TV shows in the world.

D. Expedition Robinson was the first reality TV show in the world.

4. It can be concluded from the passage that _____.

A. everyone is happy about reality TV

B. reality TV will do well in many countries

C. all the people in Europe are in favor of reality TV

D. reality TV will not be broadcast in any countries

单项选择题