在做“测量平均速度”的实验中，实验过程如图所示，计时器的最小_爱下问搜题

搜题请搜索小程序“爱下问搜题”

问题问答题

在做“测量平均速度”的实验中，实验过程如图所示，计时器的最小刻度为1s，在该次实验中，小车通过全程的平均速度v₁=______m/s；小车通过上方一半段路程S₂的平均速度v₂₌______m/s；小车通过下方一半段路程的平均速度v₃₌______m/s，通过计算可以得到，该小车滚下时做的是______运动（选填“匀速直线”或“变速直线”）．

答案

小车通过全程：路程s₁=0.6m，时间t₁=5s，故全程的平均速度v₁=

0.6m

5s

=0.12m/s；

小车通过上方一半段路程：路程S₂=0.3m，时间t₂=3s．故通过上方一半段路程的平均速度v₂=

s2

t2

=

0.3m

3s

=0.1m/s；

小车通过下方一半段路程：路程s₃=0.3m，时间t₃=2s，故小车通过下方一半段路程的平均速度v₃=

s3

t3

=

0.3m

2s

=1.5m/s；

由上述计算可知，小车在下滑过程中速度越来越快，故其运动为变速直线运动．

故答案为：0.12；0.1；0.15；变速直线．

问答题

一位物理教师在课堂上问学生：“把一块铁块和一块木块放在水里，会出现什么情况”学生回答：“铁块下去，木块浮在水面上。”“为什么呢”“因为铁重。”“而钢铁制的巨轮也很重，为什么却浮在水面上呢”这一问，学生的情绪一下子高涨起来，开始积极地思考，之后，教师再引出“阿基米德原理”。
这一教学实例体现了什么教学原则

完形填空

China is known as a country of etiquette (礼节) and ceremonies. Here is an interesting story that shows this. Once upon a time, a man   36  on a long trip to visit his friend and took a swan as a gift. But the swan   37  from its cage on the way and when he tried to   38   it, he got hold of nothing but a   39 . Instead of returning home, he continued his    40  taking the swan feather with him. When his friend received this   41  gift, he was deeply moved. And the   42  ‘The gift is nothing much, but it’s the thought that counts.’ was   43  far and wide.
Chinese used to   44  one hand in the other in front of the chest as a salute. This      45  has a history of more than 2,000 years but nowadays it is   46  used except on the Spring Festival. And shaking hands is more popular and   47  on formal occasions. Bowing was often used by people in a   48  position such as subordinates(下属), students, and attendants.   49  at present Chinese youngsters tend to simply nod as a greeting.
It is common social practice to   50  the junior to the senior, or the familiar to the unfamiliar. When you start a talk   51   a stranger, topics such as weather, food, or    52  are a good choice to break the ice. With a   53 , a chat about current affairs, sports, the stock market or his job usually goes   54 . Similar to Western customs, you should be   55  in asking a woman private questions. However, talking about her job or family life will never put you into danger.

A．appropriate

B．satisfactory

C．unfortunately