如图所示，在曲轴上悬挂一个弹簧振子，若不转动把手，让振子上下振动，其振动周期为T

发布时间：2017-04-23 08:39 │ 来源：www.tikuol.com

题型：选择题

问题：

如图所示，在曲轴上悬挂一个弹簧振子，若不转动把手，让振子上下振动，其振动周期为T₁，现使把手以周期T₂匀速转动（T₂＜T₁），当运动稳定后

[ ]

A．弹簧振子振动周期为T₁

B．弹簧振子振动周期为（T₁+T₂）/2

C．要使弹簧振子振幅增大，可让把手转速减小

D．要使弹簧振子振幅增大，可让把手转速增大

考点：共振

题型：选择题

信息归纳。

Dear Dad and Mum,
     How are you? I hope you are well. I have been in Beijing for about two months and I enjoy living here
very much. The weather here is pretty cold and people are friendly. I work and study with Chinese students.
On the weekends I play different kinds of sports. Ping-pong is one of the most popular sports here. Now,
I am learning playing ping-pong from my best friend Li Ming. He is very good at playing it. He also asks me
to teach him to play basketball. I also learn Chinese from my classmates and at the same time teach them
Japanese. Last week, I visited many places of interest. They are really great. I like them very much. My
favourite places are the Bird's Nest and the Great Wall. It is amazing, isn't it? I saw Beijing Opera with my
teacher yesterday and enjoyed delicious Chinese food. Beijing roast duck is the most delicious. Now I have
known more about Chinese history. Hope to meet you soon.
     Best wishes!
                                                                                                                                              Yours,
                                                                                                                                              Tom

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2. Tom learns table tennis from	2. ____________________________.
3. In Beijing, the weather is	3. ____________________________.
4. What places does Tom like best?	4. ____________________________.
5. What did Tom see yesterday?	5. ____________________________.

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