问题 选择题

我国曾发射一颗绕月运行的探月卫星“嫦娥1号”。设想“嫦娥1号”贴近月球表面做匀速圆周运动,其周期为T。“嫦娥1号”在月球上着陆后,自动机器人用测力计测得质量为m的仪器重力为P。已知引力常量为G,由以上数据可以求出的量有(       )

A.月球的半径

B.月球的质量

C.月球表面的重力加速度

D.月球绕地球做匀速圆周运动的向心加速度

答案

ABC

题目分析:A、由可以求出月球的半径;正确

B、由可以求出月球的质量;正确

C、由P=mg可以求出月球表面的重力加速度;正确

D、没有给出月球与地球间的关系,所以不能求出月球绕地球做匀速圆周运动的向心加速度;错误

故选ABC

点评:中等难度。把卫星的运动看成匀速圆周运动,万有引力提供向心力,通过测卫星的周期T、轨道半径r,则可推导出天体质量及密度,但只能求中心天体的质量和密度;若卫星在天体表面运行,只测出其周期即可。在天体表面,万有引力近似等于物体的重力。

阅读理解

阅读理解

     I made a promise to myself on the way down to the vacation beach cottage.For two weeks I would try

to be a loving husband and father.Totally loving.No ifs,ands or buts.

     The idea had come to me as I listened to a talk on my car radio.The speaker was quoting a Biblical

passage about husbands and their wives.Then he went on to say,"Love is an act of will.A person can

choose to love." To myself,I had to admit that I had been a selfish husband.Well,for two weeks that would change.

     And it did.Right from the moment I kissed Evelyn at the door and said,"That new yellow sweater looks

great on you.""Oh,Tom,you noticed",she said,surprised and pleased.Maybe a little puzzled.After the long

drive, I wanted to sit and read. Evelyn suggested a walk on the beach. I started to refuse, but then I

thought "Evelyn's been alone here with the kids all week and now she wants to be alone with me. " We

walked on the beach while the children flew their kites.

     So it went.Two weeks of not calling the Wall Street firm where I am a director;a visit to the shell

museum though I usually hate museums.Relaxed and happy,that's how the whole vacation passed.I made

a new promise to keep on remembering to choose love.

     There was one thing that went wrong with my experiment,however.Evelyn and I still laugh about it

today.On the last night at our cottage,preparing for bed,Evelyn stared at me with the saddest expression.

     "What's the matter?" I asked her.

     "Tom," she said in a voice filled with distress,"I don't?"

     "What do you mean?"

     "Well...that checkup I had several weeks ago...our doctor...did he tell you something about me?Tom,

you've been so good to me...am I dying?"

     It took a moment for it all to be understood.Then I burst out laughing.

     "No,honey," I said,wrapping her in my arms."You're not dying;I'm just starting to live."

1.In the first paragraph,"No ifs,ands or buts" probably means________.

A.Unintentionally  

B.Independently

C.Impressively  

D.Unconditionally

2.From the story we may infer that Tom drove to the beach cottage________.

A.with his family  

B.with Evelyn

C.alone  

D.with his children

3.During the two weeks on the beach,Tom showed more love to his wife because________.

A.he was determined to be a good husband

B.he had made a lot of money in his Wall Street firm

C.she looked lovely in her new clothes

D.the doctor said his wife was seriously ill

4.The author says,"There was one thing that went wrong with my experiment." What does "one thing"

refer to?

A.He praised her sweater,which puzzled her.

B.She insisted on visiting a museum,which he hated.

C.He knew something about her illness but didn't tell her.

D.He was so good to her that she thought she must be dying.

5.By saying "I'm just starting to live," Tom means that________.

A.he is just beginning to understand the real meaning of life

B.he is just beginning to enjoy life as a loving husband

C.he lived an unhappy life before and is now starting to change

D.he is beginning to feel regret for what he did to his wife before

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