问题 选择题

物体在周期性驱动力作用下做受迫振动,固有频率为f1,驱动力的频率为f2,物体做受迫振动的频率为f,则

A.f = f1

B.f = f2

C.f>f1

D.f<f2

答案

答案:B

题目分析:物体做受迫振动的频率等于驱动力的频率,则受迫振动的频率为f=f2,B正确

点评:难度较小,明确驱动力的频率决定受迫振动的频率,当驱动力的频率与受迫振动的频率相等时发生共振现象,振幅最大

选择题
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Apollo

For lovers of the arts, Apollo is a truly necessary magazine. Covering the ages and the great civilizations of the world, Apollo brings you well-illustrated yet academic articles by internationally famous scholars, as well as information on exhibitions and sales. Experience five monthly issues for as little as £ 5 each.

The Guardian Weekly

The Guardian Weekly gives you a global view with articles from four of the world’s most respected newspapers. Read the news from different views and draw your own conclusions on the stories shaping our world. Try it for 3 months for just £15.55. Plus get a free copy of The Guardian Year 2003.

New Internationalist

Full of excellent writing and photography, the NI covers one key subject each month, from Terrorism to Poverty to Climate Change.

Reporters from around the globe provide you with a comprehensive world view. PLUS: Masses of fresh reports and stories to keep you up-to-date on world affairs. 3 months free and free World Map.

The Week

The Week is the only weekly summary giving you the best of the British and foreign newspapers in just 35 pages. Designed to be read in just 1 hour, it provides you with everything you need and want to know. Try The Week now with 13 issues for just £ 13.75.

If you decide it’s not for you, just tell us within the first 6 weeks and you can get your money back.

小题1:1Which of the following magazines will probably provide you with articles about music and paintings?

A.Apollo.

B.The Week.

C.New Internationalist.

D.The Guardian Weekly.小题2:It is possible that most of the readers of the four magazines are ____.

A.men

B.women

C.children

D.grown-ups小题3:Which of the following would you most probably read if you want to get information from the world’s most popular newspapers?

A.Apollo & The Week.

B.Apollo & New Internationalist.

C.The Guardian Weekly & New Internationalist

D.The Guardian Weekly & New Internationalist小题4: The purpose of writing these four texts is to ____.

A.tell the readers the latest news

B.get more readers to subscribe(订阅)

C.show the importance of the four magazines

D.introduce the four magazines to new readers