试题与答案

一物理兴趣小组用以下装置测量滑块与长为L=1m的轨道之间的滑动摩擦因数以及探究滑

题型:实验题

题目:

一物理兴趣小组用以下装置测量滑块与长为L=1m的轨道之间的滑动摩擦因数以及探究滑块在沿轨道向上运动时所受合力做功与动能变化的关系。

(1) 测量滑块与轨道之间的滑动摩擦因数。

轨道上安装有两个光电门,其中光电门1的位置可移动。当一带有宽度为d=1cm的遮光条的滑块自轨道上滑下时,与两个光电门都相连的计时器可以显示出遮光条通过光电门1、2所用的时间分别为Δt1、Δt2。使滑块以一定初速度下滑,调节轨道右端距桌面的高度,最终使Δt1 =Δt2 ,并用米尺测量出轨道右端距桌面的高度h="25cm" ;则滑块与轨道之间的滑动摩擦因数 μ=________;

(2) 探究滑块在沿轨道向上运动时所受合力做功与动能变化的关系。

撤掉光电门2,保持实验(1)中h不变,在轨道右端安装一光滑的定滑轮,用细绳连接滑块与力传感器(与电脑相连,其所受拉力可直接由电脑显示),细线横跨过定滑轮,传感器连接一重物,如图所示,操作:遮光条与光电门1距离x可从刻度尺上读出,通过改变光电门的位置,来获得多组数据;每次均由轨道底(低)(此处最好改为同一位置)端无初速度释放滑块,与光电门相连的计时器显示出每次遮光条通过光电门1所用的时间Δt,并做好记录,如下表所示

 第一次第二次第三次第四次
x(cm)10.022.650.062.4
Δt(s)0.01010.00670.00450.0040
V(m/s)0.991.502.24 
①请你根据以上题干中及图表内的信息,求解第四次实验中获得的速度= ________;(保留三位有效数字)

②要验证受合力做功与动能变化的关系,还需要测出的物理量是(     )

A.力学传感器的质量

B . 滑块与遮光条的质量

C.重物的质量

D. 滑块每次从静止开始滑到光电门所用的时间

③一位同学每次实验得到力传感器的数值都为19.8N,并根据以上图表中数据做出了v2----x图像,如图所示。根据图像请你求出滑块的质量M=________;(重力加速度g=9.8m/s2

答案:

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答案:D题目分析:本题考查的大河文明—人类文明的摇篮内容。四个选项中A选项可以首先排除,因为金字塔是亚非文明的的成果,亚马孙河在南美洲,剩下三个选项中,两河流域诞生的文明古国是古巴比伦,文明成果有《...

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Cohn Blanchard stood up from the bench, straightened his Army uniform, and studied the crowd of people making their way through Grand Central Station. He looked for the girl whose heart he knew, but whose face he didn’t, the girl with the rose.

His interest in her had begun thirteen months before in a Florida library. Taking a book off the shelf he found himself intrigued, not with the words of the book, but with the notes penciled in the margin. The soft handwriting reflected a thoughtful soul and insightful mind. In the front of the book, he discovered the previous owner’s name, Miss Hollis Maynell. With time and effort he located her address. She lived in New York City. He wrote her a letter introducing himself and inviting her to correspond. The next day he was shipped overseas for service in World War II.

During the next year and one month the two grew to know each other through the mail. Each letter was a seed falling on a fertile heart. A romance was starting Blanchard requested a photograph, but she refused. She felt that if he really cared, it wouldn’t matter what she looked like.

When the day finally came for him to return from Europe, they scheduled their first meeting —7:00 PM at the Grand Central Station in New York. “You’ll recognize me,” she wrote, “by the red rose I’ll be wearing on my lapel.” So at 7:00 he was in the station looking for a girl whose heart he loved, but whose face he’d never seen.

I’ll let Mr. Blanchard tell you what happened: A young woman was coming toward me, her figure long and slim. Her blonde hair lay back in curls from her delicate ears; her eyes were blue as flowers. Her lips and chin had a gentle firmness, and in her pale green suit she was like springtime come alive. I stared at her, entirely forgetting to notice that she was not wearing a rose. As I moved, a small, attractive smile curved her lips. “Going my way , sailor?” she murmured.

Almost uncontrollably I made one step closer to her, and then I saw Hollis Maynell. She was standing almost directly behind the girl. A woman well past 40, she had graying hair tucked under a worn hat. She was more than plump, her thick-ankled feet thrust into low-heeled shoes. The girl in the green suit was walking quickly away. I felt as though I was split in two, so keen was my desire to follow her, and yet so deep was my longing for the woman whose spirit had truly companioned me and upheld my own.

And there she stood. Her pale, plump face was gentle and sensible, her gray eyes had a warm and kindly twinkle. I did not hesitate. My fingers gripped the small worn blue leather copy of the book that was to identify me to her.

This would not be love, but it would be something precious, something perhaps even better than love, a friendship for which I had been and must ever be grateful. I squared my shoulders and saluted and held out the book to the woman, even though while I spoke I felt choked by the bitterness of my disappointment."I'm Lieutenant John Blanchard, and you must be Miss Maynell. I am so glad you could meet me; may I take you to dinner?"

  The woman's face broadened into a tolerant smile. "I don't know what this is about, son," she answered, "but the young lady in the green suit who just went by, she begged me to wear this rose on my coat. And she said if you were to ask me out to dinner, I should go and tell you that she is waiting for you in the big restaurant across the street. She said it was some kind of test!"

It's not difficult to understand and admire Miss Maynell's wisdom. The true nature of a heart is seen in its response to the unattractive. "Tell me whom you love," Houssaye wrote, "And I will tell you who you are. "

小题1:How did John Blanchard get to know Miss Hollis Maynell?

A.They were both interested in literature.

B.John knew Hollis's name from a library book.

C.John came across Hollis in a Florida library .

D.They lived in the same city.小题2:Hollis refused to send Blanchard a photo because            .

A.she thought true love is beyond appearance

B.she had never taken any photo before they knew

C.she was only a middle - aged woman

D.she wasn't confident about her appearance小题3:How could Blanchard recognize Hollis?

A.She would be wearing a scarf around her neck.

B.She would be holding a book in her hand.

C.She would be standing behind a young girl.

D.She would be wearing a rose on her coat.小题4:What was the real Miss Hollis Maynell like?

A.She was a middle - aged woman in her forties.

B.She was a young, pretty girl wearing a green suit.

C.She was a plump woman with graying hair.

D.She was a slightly fat girl, with blonde hair.小题5:When Blanchard went over to greet the woman, he was         

A.shocked but inspired

B.annoyed and bad - mannered

C.disappointed but well - behaved

D.satisfied and confident小题6:Which of the following can be the best title for the passage?

A.Love is blind

B.Don't Judge a Book by its Cover

C.A Test of Love

D.The Symbol of Rose

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