问题 实验题

通过实验我们已经知道滑动摩擦力与压力有关,也与接触面的粗糙有关.有的同学猜想滑动摩擦力可能还与接触面的大小有关,请你从以下器材中选出部分器材,设计一个实验对此猜想进行检验.器材:

a.斜面;

b.带钩的正方体木块;

c.带钩的长方体木块;

d.长木板;

e.几条手巾;

f.刻度尺;

g.弹簧测力计.

(1)你所需要的实验器材(填写字母): _________

(2)简述主要实验步骤:

答案

(1)c、d、 g

(2)

 A:将长方体木块平放在长木板上,用弹簧测力计拉着长方体木块做匀速直线运动,读出弹簧测力计的示数,记为F1

B:将木块侧放在长木板上,用弹簧测力计拉着长方体木块做匀速直线运动,读出弹簧测力计的示数,记为F2

C:将长方体木块竖放在长木板上,用弹簧测力计拉着长方体木块做匀速直线运动,读出弹簧测力计的示数,记为F3

D:比较F1与F2与F3,若F1=F2=F3,则滑动摩擦力与接触面积无关;若F1=F2=F3,则滑动摩擦力与面积有关.

阅读理解

阅读理解。

     Jack London is a famous American writer. He was born on January 12, 1876, in San Francisco,

California. His family was very poor, and Jack had to leave school to make money. He worked hard

in many different jobs.

     Later, Jack returned to school, but he didn't stay there. In 1897, he went to Alaska to find gold. He

didn't find any gold (金). Instead(代之的), he found ideas for his books and stories. He returned home

and started to write. His writings were successful(成功的), and he became rich (富有的) and famous in

his twenties.

    Jack London was not a happy man. In poor health, he took his own life in 1916. He was only 40

years old.

1. Why did Jack London leave school when he was still a boy?

A. Because he had a poor family          

B. Because he didn't like to go to school

C. Because his father was a very bad man 

D. Because he was too young to go to school

2. How old was Jack London when he went to Alaska?

A. Eighteen years old            

B. Twenty-one years old

C. Twenty-four years old        

D. Twenty-three years old

3. What did Jack London find in Alaska?      

A. Gold        

B. Sliver (银)    

C. Material      

D. His friend

4. Why was Jack London famous?

A. For his journey in Alaska            

B. For his hard work

C.  For his writings                  

D. For his wealth

5. What does "he took his own life" mean?      

A. He lived a poor life    

B. He enjoyed his life  

C. He died  

D. He killed himself

判断题