问题 探究题

在探究“滑动摩擦力的大小与哪些因素有关”的实验中,某同学利用如图所示器材和步骤a、b、c、d进行了实验探究.请通过观察和比较回答下列问题:

(1)为探究滑动摩擦力的大小与接触面粗糙程度之间的关系,可利用步骤  和步骤  ,得出的结论是                                                      

(2)为探究滑动摩擦力的大小与压力大小之间的关系,可利用步骤  和步骤  ,得出的结论是                                                                         

(3)为探究滑动摩擦力的大小与接触面积大小之间的关系,可利用步骤  和步骤  ,得出的结论是                                                 

(4)本实验采用的实验方法                                        

答案

(1)a;c;压力一定时,接触面越粗糙,摩擦力越大;

(2)c;d;接触面粗糙程度一定时,压力越大,摩擦力越大;

(3)a;b;摩擦力的大小与接触面积的大小无关;

(4)控制变量法、转换法.

阅读理解

阅读理解。

  A 50-year-old American officer (官员) came back to his school. The

teacher asked him to give a talk to the small boys and girls there. The talk was

about the love of' their great country. All the little   ones were sitting in a large

meeting-room. The old officer went up and began speaking. He said, " boys and

girls,  I studied in this school forty years ago. When I was your age, we were not

as happy as you are today. Think about it and answer me, why are you so happy

now?"

  No sound came from the children. The old man waited for a long time. Then

a short boy in the front put up his small dirty hand. "Good boy! Please answer

me, dear. " said the officer.

  With a big smile on his face, the boy stood up and said, "if you speak long

enough, we won't have math and  biology  (生物学) lessons this morning. "

1. The old man came back to school _____.

A. to listen to a talk       

B. to have lessons

C. to give a talk          

D. to see his children

2. The officer studied in this school when he was _____

A. fifty                      

B. ten

C. twenty                    

D. children

3. The children were _____ before.

A. as good as              

B. as well as

C. as happy as            

D. much happier than

4. The short boy in the front _____.

A. didn't understand the question and answer it

B. told the truth

C. wanted to make others laugh

D. wanted to make the officer angry

5. After reading the last part of' the story, we know that _____.

A. the short boy liked the talk very much

B. all the children liked the talk

C. the short boy didn't like studying his lessons

D. some of' the children liked to listen to a funny story

问答题