问题 实验题

《用DIS研究机械能守恒定律》的实验中:

(1)下列说法中正确的是[ ]

A.摆锤每次都必须从摆锤释放器的位置以不同的速度向下运动

B.必须测定摆锤的直径

C.摆锤下落的高度可由标尺盘直接测定

D.定位挡片的作用是改变摆锤的机械能

(2)某同学实验得到的数据界面如图(b)所示,在数据要求不太高的情况下,可得出结论:________________________,理由是:________________________。

(3)经过仔细研究数据发现,摆锤从A到D的过程中机械能____________,造成这种情况的原因主要是________________________。

答案

(1)BC

(2)只有重力做功的情况下,物体的机械能保持守恒;计算出摆锤在A、B、C、D四点的机械能分别为1.125×10-2 J、1.11×10-2 J、1.08×10-2 J、1.05×10-2 J,各点机械能大小基本一致

(3)逐渐减小,摆锤克服空气阻力做功消耗一定的机械能

阅读理解

I remember my math teacher Mr. Young very well. He stood out because the kids made fun d him. He was missing one of his fingers, and always pointed at students with his middle finger.

I was not very good at English and math. No matter how hard I tried, I just could not figure out why I did not understand what all the other kids found so easy to learn.

One day, I was told that if I got one more E on my report card, I would be taken to the “big person for kids”

I tried really hard for weeks. I just couldn't understand how to make different parts of members into whole things.

The day before report cards were to come out, 1 knew that Mr. Young would give me an E, just like he always did.

I went to Mr Young and told him that the orphanage (孤儿院) was going to send me to the big person if I got another E on my report card. He told me there was nothing he could do; it would be unfair to the other kids if he gave me a better grade than I had actually earned.

I smiled at him and said, "Mr. Young, do you know how the kids make fun of you because you’re missing your finger?" He looked at me, moved his mouth to one side and said nothing.

“They shouldn’t do that to you because you can't help having a finger, Mr. Young. Just like I can’t help not being able to learn numbers and stuff like that.” I said

The next day, when I got my report card, I tucked it into one of my books. While on the school bus, I opened it: Geography, B+; Mechanical Drawing, C-; English, D-l; History, C-; Gym, B+; Art, C; Math, D-.

That math grade was the most favorite one I ever received. Because I knew that someone in the world finally understood what it was like for me to be missing a finger inside my head.

59. From the second paragraph we can infer that the boy is _________ in some subjects.

A. mind-blowing (给人印象极深的 )         B. slow-witted (头脑迟钝的)

C. fun-loving                                     D. badly- behaved

60. Where may the boy live according to the passage?

A. In an orphanage.                                         B. In a big prison.        

C. In the school dormitory.                               D. In his home.

61. What grade should the boy have got in the math test this time?

A. D-.                  B. B +               C. D.                     D. E.

62. The underlined word "tucked" in the passage most probably means “________”.

A. stuck             B. listed               C. hid                   D. copied

63. The reason why the boy remembers Mr Young is that ________.

A. he missed one of his fingers                      B. he treated his students very well

C. he understood the boy                   D. he taught his students in a special way

问答题 简答题