试题与答案

像打点计时器一样,光电计时器也是一种研究物体运动情况的常用计时仪器,其结构如图甲

题型:填空题

题目:

像打点计时器一样,光电计时器也是一种研究物体运动情况的常用计时仪器,其结构如图甲所示,a、b分别是光电门的激光发射和接收装置,当有物体从a、b间通过时,光电计时器就可以显示物体的挡光时间.

现利用图乙所示装置测量滑块和长1m左右的木块间的动摩擦因数,图中MN是水平桌面,Q是木板与桌面的接触点,1和2是固定在木板上适当位置的两个光电门,与之连接的两个光电计时器(没有画出).此外在木板顶端的P点还悬挂着一个铅锤,让滑块从木板的顶端滑下,光电门1、2各自连接的计时器显示的挡光时间分别为5.0×10-2s和2.0×10-2s.用游标卡尺测量小滑块的上部挡板的宽度d,卡尺数如图丙所示.

(1)读出滑块挡板的宽度d=______cm.

(2)滑块通过光电门1的速度v1=______m/s,滑块通过光电门2的速度v2=______m/s.

(3)若仅提供一把米尺,已知当地的重力加速度为g,为完成测量,除了研究v1、v2和两个光电门之间的距离L外,还需测量的物理量是______(说明各量的物理意义,同时指明代表物理量的字母).

(4)用(3)中各量求解动摩擦因数的表达式μ=______ (用字母表示).

答案:

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参考答案:渗透压

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题型:阅读理解

阅读下列短文,从每题所给的A、B、C、D四个选项中,选出最佳选项。

D

The first MP4 player was born years ago. Soon many music fans were wondering how fantastic it is! If you have been into technology enough, perhaps you may have a knowledge of the MP4. If not, you do need to know something before buying one, even if you are familiar with MP3. MP3 is the CD-like disc with greater capacity. How about MP4? This small digital product will really enrich the joy from listening to music. You can even feel the “touch” of music to your soul!

Now, some similar digital products advertised as “MP4 player” are simply MP3 players, which do not play video and MPEG format and also lack other particular functions. These products confuse some buyers, as they may think the “MP4” players simply mean they can do more than MP3.

What is MP4?

It is a multimedia container. It is not only used to store digital audio and digital video streams, especially those of MPEG, but can also be used to store other data such as subtitles and pictures. As a most modern container format, it allows streaming over the Internet.

With the help of a piece of MP4 video equipment, you can change various programs such as MPEG to MP4, ASX to MP4, AVI to MP4 and so on, which can be done very quickly and easily without any effect on the sound quality. By installing DVD-MP4 software, you can transfer particular music from a DVD to an MP4 video file. It really excites your listening music experience.

Then, there is MP4 advanced and you can set your own collection of all the programs—TV shows, games, and music. You can even see movies which are still running in cinema. What else digital product could you possibly ask for?

小题1: It is suggested here that you should ______ before buying an MP4 player.

A.first be a music fan

B.have a knowledge of MP4

C.get familiar with MP3

D.buy a CD-like disc小题2:From the passage, we can see that MP4 is ______ MP3.

A.much bigger than

B.just as advanced as

C.not so particular as

D.more functional than小题3:Which function of MP4 is NOT directly mentioned in this passage?

A.Storing digital audio and video streams.

B.Recording some movies in cinema.

C.Playing TV shows, games and movies.

D.Transferring particular music from a DVD.

小题4:From the last sentence, it’s clear that the writer tries to tell us it is ______.

A.reasonable to buy other digital products

B.impossible to buy something else

C.a very wise choice to buy an MP4

D.an exciting experience to buy an MP3

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