问题 填空题

用弹簧测力计拉着重100N的物体在水平面上向左运动,物体以lm/s的速度匀速前进时,弹簧测力计示数为2N,当该物体仍在该水平面上以2m/s的速度匀速向左运动时,它受到摩擦力的大小是______N,方向是水平向______.

答案

弹簧测力计拉着物体以lm/s的速度匀速前进时,弹簧测力计示数为2N,说明此时摩擦力也为2N,当该物体仍在该水平面上以2m/s的速度匀速向左运动时,因为压力和接触面的粗糙程度不变,所以其受到的摩擦力不变,仍为2N,方向向右.

故答案为:2;右.

阅读理解

任务型阅读。

根据短文内容,从短文后的选项中选出能填入空白处的最佳选项。选项中有两项为多余选项。

     "OK, class. Count off (报数)by five."   1   Sometimes, breaking into small groups lasts as long as the class

does. Other times, it signals the start of a"group project"-which means you'll be working with a few classmates

for a day, several days, or longer on an assignment (任务). 

       2   Most things are done with the help or ideas of other people. Group projects are great practice for high

school, college, and real life, when you will probably have a job that requires working with others. Right now,

group projects can be fun and they often allow you to do a bigger, more interesting project than you could

alone.   3        

     Group projects also give you a chance to get to know kids you might not know or talk with-maybe the

quiet kid in the third row, or the boy who lived down the street when you were in kindergarten.   4   For

example: working on a deadline (最后期限),staying organized, or being patient. And if you're a little nervous

talking in front of a group, a joint (联合的) project can help you become more comfortable with it. 

       5    If so, you'll know your whole group is rooting for you!

A. Few of us act alone in the real world.

B. Why is this type of project so popular in school?

C. With group work, you can actually learn more in less time.

D. Maybe your group will pick you to tell the whole class about your project.

E. Group projects are also a great way to practice skills you're not so sure of.

F. When your teacher gives you that instruction, you know what's coming next.

G. One key to a good meeting is having a leader, who should help the group stay focused.

判断题