在游乐场中有一种旋转飞椅,如图所示,在半径为r的平台边缘固定着长为L的绳子,另一

题型:问答题

问题:

在游乐场中有一种旋转飞椅,如图所示,在半径为r的平台边缘固定着长为L的绳子,另一端则是由小朋友乘坐的椅子,若绳子与竖直方向夹角为θ,当平台绕其中心轴旋转时,问:

(1)若小朋友的质量为m,绳子的拉力为多大?

(2)该平台的旋转的角速度是多大?

考点:向心力牛顿第二定律
题型:问答题

假如英语课上老师要求同学们交换修改作文,请你修改同桌写的以下作文。文中共有10处语言错误,要求你在错误的地方增加、删除或修改某个单词。

增加:在缺词处加一个漏字符号(∧),并在其下面写上该加的词。

删除:把多余的词用斜线(\)划掉。

修改:在错的词下划一横线,并在该词下面写上修改后的词。

注意:1.每处错误及其修改均仅限一词;

2.只允许修改10处,多者(从第11处起)不计分。

My spare time is full of interested activities. I read all kinds of books in reading-room whenever I have time. I learn much in the library than in class in this way. Sports and games keep me health enough to deal with all difficulties. My favourite was volleyball among all games. I often play with volleyball after school. Sometime I go in for social practice with my classmates outside school. Thus I can gain some social experiences.

Out-of-class activities are quite necessary for our students. Through these activities we can learn many things that can’t learned in class.

题型:问答题

栽植裸根苗木应将苗木栽正扶直,深浅适宜,根系舒展,先填表土湿土,后填新土干土,分层覆土,层层踏实,最后覆一层()。

A、石子

B、细土

C、树叶

D、石灰

题型:问答题

十二经脉中,六阳经均不经过手(足)掌部。( )

题型:问答题

下列组合中正确的是

A.钨酸钙——感蓝片

B.钨酸钙——感绿片

C.硫氧化钆——感蓝片

D.高电压摄影增感屏——正色片

E.稀土增感屏——感蓝片

题型:问答题

在下图所示的四种基本组态放大电路框图中,选出两种组成两级放大电路,满足输入电阻低,输出电阻低,Au1Au2>1。要求:

(1)画出满足要求的两级放大电路的框图;

(2)说明两级放大电路框图设计的理由。

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