搜题请搜索小程序“爱下问搜题”
问题 计算题

如右图所示，质量M＝kg的物块A套在水平直杆上，并用轻绳将物块A与质量m＝kg的小球B相连接．现用跟水平方向成＝30°夹角、大小为F＝N的力，拉着小球B并带动物块A一起向右做匀速直线运动．若在运动过程中，A、B的相对位置始终保持不变，重力加速度g＝10m/s2，试求：

⑴轻绳与水平方向间的夹角；

⑵物块A与直杆间的动摩擦因数．

答案

⑴30°       ⑵

补全对话，情景问答
补全对话
A. Why don't you go to the computer museums?
B. I don't like science museums.
C. History museums are boring.
D. What kind of museums do you like history? Science? A children's museum?
E. I think we can get there by taxi.
F. That's great idea!
G. What about history museum?
Mother: Could you tell me if there is a good museum in Sunville?
Clerk: Well, we have several.    1   
Father: How about history? I like history museums. They're fascinating.
Girl1: Or, Dad    2   . Let's go to the children's museum.    3   . I want to go to the children's museum, They're more fun.
Gir12: Well, I'm too old for a children's museum. Why don't we go to an art museum?
Clerk:    4    There are a lot of fun things for children there, you can learn all about the history of computers, as well
           as learn about science.
Family:    5    Let's go to the computer museum.
查看答案
单项选择题

胃管吸取的D液是指（）。

A.十二指肠液

B.胆总管液

C.胆囊液

D.肝胆管液

E.胃液
查看答案