问题 问答题

某同学做“探究弹力和弹簧伸长量的关系”的实验

(1)实验中要用毫米刻度尺测弹簧原长,应采用如图______方法(填“1”或“2”)

(2)若你用了(1)中的某种方法测原长,用直尺测出弹簧的原长L0,再把弹簧竖直悬挂起来,挂上钩码后测出弹簧伸长后的长度L,把L-L0作为弹簧的伸长量x,这样操作,最后画出的图线可能是图3中的______

(3)无论你在(1)中采用何种方法,采用(2)中的方法作出图线,根据图线求出劲度系数是否相同?______(填“相同”或“不相同”)

答案

(1)由于重力的影响,不挂重物时弹簧竖直比水平要稍微长一些,

由于实验时是把弹簧竖直悬挂起来,所以测量原长时也要把弹簧竖直悬挂起来,故应采用图2方法;

(2)根据胡克定律:F=Kx,结合数学知识知F-x图象应是过原点的直线,故A正确,

故选:A.

(3)由F=Kx,则K=

△F
△x
,即F-x图线的斜率等于弹簧劲度系数大小,采用图1方法测量出的弹簧原长偏小,造成F-x图象在坐标轴上有一定截距,但不影响斜率大小.故测出的劲度系数相同;

故答案为:(1)2;(2)A;(3)相同.

多项选择题
阅读理解

阅读下面的材料,从每题所给的A、B、C三个选项中,选出最佳选项回答问题或完成句子。

     I will never forget the lesson about my window. Four years ago, I moved to a house in a large town.

One of my new neighbors’ house was only a few feet away from mine. There lived a woman. Through

one of my windows, I could see her reading by her window every afternoon.    

     Several months later, I found I couldn’t see the woman clearly. I thought her window was too dirty.

I said to myself, “Why doesn’t she clean her window? It looks terrible!”

     One afternoon, I decided to clean my house including(包括) the window. I felt tired after three hours

of hard work. So I sat down by the window for a rest. What a surprise! I could see the woman reading

there clearly again! By that time, I realized that my own window was too dirty, not hers! I really felt

ashamed for myself. I had been watching her through my dirty window in the past days!

     The experience is very important for me. So I try to clean the window of my heart before judging

(评判) others.

1. How long has the writer lived in the house according to the passage?

A. Two years.  

B. Three years.  

C. Four years.    

2. The writer couldn’t see the woman clearly because ________.

A. the writer’s window was dirty              

B. the woman’s house was too far

C. the woman didn’t open her window

3.The underlined word “ashamed” means _________.

A. 高兴的 

 B. 放松的  

C. 羞愧的

4. According to the passage, the writer has learnt how to _________.

A. clean the house  

B. judge others  

C. help neighbors