全自动洗衣机可以自动实现进水、洗涤等工序．洗衣机的进水是通过_爱下问搜题

搜题请搜索小程序“爱下问搜题”

问题问答题

全自动洗衣机可以自动实现进水、洗涤等工序．洗衣机的进水是通过控制器实现自动控制的．如图所示为一种洗衣机水位控制器的原理示意图，洗衣机进水前粗细均匀的塑料管内充满空气，当洗衣机进水时，洗衣桶内的水位上升，塑料管中空气的压强______（选填“增大”、“减小”或“不变”），当水位上升到一定高度时，水位控制器根据压强传感器向外输出的信号，切断进水阀电磁线圈的电路，使进水停止并转入其它工作程序．若不计细塑料管下部水平部分长度，当洗衣桶内的水位达到一定深度时，水进入塑料管的高度为1.75cm，压强传感器测得的气体压强是1.03×10⁵Pa，则塑料管的长度是______cm．（设水的密度是1.0×10³kg/m³，大气压强是1.0×10⁵Pa）

答案

当洗衣机进水时，洗衣桶内的水位上升，塑料管中空气的体积减小，根据气体方程

PV

T

=C得塑料管中空气的压强增大．

当洗衣桶内的水位达到一定深度时，水进入塑料管的高度为1.75cm，设塑料管的长度是xcm

根据气体方程

PV

T

=C得：

P₀x•S=P₁（x-1.75）•S

解得：x=60cm．

故答案为：增大，60cm．

完形填空

A Love Note To My Mom
When I was a little girl, I would often accompany you as you modeled for fashion photographers. It was years later that I finally understood what role modelling 36 in your life. Little did I know you were 37 every penny you earned to go to 38  school.
I cannot thank you enough for 39 you told me one autumn afternoon when I was nine. After finishing my homework, I went into the dining room where you were buried 40  piles of law books. I was 41  .Why were you doing what I do—memorizing textbooks and studying for 42  ? When you said you were in law school, I was more puzzled. I didn’t know. Moms could be lawyers too. You smiled and said, “In life, you can do anything you want to do.”
As young as I was, that statement kept 43 in my ears. I watched as you faced the 44 of completing your studies, starting companies with Dad, while still being a 45 and a Mom with five kids. I was exhausted just watching you in action. With your words of wisdom in my youthful mind, I suddenly felt unlimited freedom to dream. My whole world 46 . I set out to live my life filled with        47  , seeing endless possibilities for personal and professional achievements.
Your words became my motto. I constantly found myself in the unique position of being either the first (woman doctor in Maryland Rotary) or one of the few women (chief medical reporters) in my field. I gained strength every time I said , “Yes, I’ll try that.”
Encouraged by your 48 , I have forged ahead (毅然前行) with my life’s journey, less afraid to make mistakes, and 49 meeting each challenge. You did it, and now I’m 50 it. So, get to run. So much to do, so many dreams to live.

D．disappointed

B．closed down

A．description

D．introduction

B．considering

单项选择题

下列物质中哪种物质的导热系数最小？（）

A.铁

B.水

C.空气

D.铜