题干

将一半径为R的实心金属球,用细线拉着,匀速缓慢地放入水深为2R的盛水容器中,直至容器底部,水未溢出。下图能反映金属球从水面刚接触处开始至容器底部过程中,所受浮力的大小F与金属球浸入水中深度h的关系的是(    )

A:

B:

C:

D:

上一题 下一题 0.0难度 选择题 更新时间:2018-01-27 03:04:22

答案(点此获取答案解析)

C

同类题2

根据短文理解,填入适当的单词。    

    Making friends is a skill. Like most skills, you can improve it if you are patient. If you want to meet people and make friends, you must be willing to take action. You must first go where there are people. You won't make friends staying home ____.

    Joining a club or a group, talking to those who like the same things as you do is much ____. Or join someone in some activity.

    Many people are ____ when talking to new people. After all, meeting strangers means seeing the unknown. And it's human nature to feel a bit unpleasant about the unknown. Most of fears about ____ with new people come from doubts  about ourselves. We imagine other people are judging us—finding us too tall or too short, too this or too that. But don't forget that they must be feeling the ____way. Try to accept yourself as you are, and try to make others feel at home. You'll all feel more ____.

    Try to be brave even if you don't feel that way when you ____ a room full of strangers. Walk tall and straight, look directly at other people and smile.

    If you see someone you'd like to speak to, say something. Don't wait for the other person to start a ____.

    Just meeting someone new does not mean that you'll make friends with that person. Friendship is based on mutual (相互的) likings and "give and take". It takes time and effort (精力)for us to ____ friendship. And there are things that stop a new friendship from ____.