问题 问答题

在“用单摆测定重力加速度”的实验中,直接测出的物理量是______,为了算出单摆振动周期,应先测出______,其中计量单摆振动时间的起止时刻,均应选在摆球通过______位置时,本实验用重力加速度的计算式是g=______.

答案

根据单摆的周期公式T=2π

L
g
,得到重力加速度为:g=
T2L
4π2

故需要测量摆长L,即摆线长、摆球直径;

经过平衡位置速度最大,时间最短,误差最小,故从经过平衡位置开始计时;

测出振动n次的时间t,则周期为:T=

t
n

故重力加速度的表达式为:g=

4π2n2l
t2

故答案为:摆线长、摆球直径(或摆长),振动n次的时间t,静止时的平衡,

4π2n2l
t2

阅读理解

( B )

“Cool”is a word with many meanings.Its old meaning is used to express a temperature that is a little bit cold.As the world has changed,the word has had many different meaning.

“Cool”can be used to express feelings of interest in almost anything.

When you see a famous car in the street,maybe you will say,“It’s cool.”You may think“He’s so cool,”when you see your favourite footballer.

We all maximize(扩大) the meaning of“cool”.You can use it instead of many words such as “new” or “surprising”.Here’s an interesting story we can use to show the way the word is used.A teacher asked her students to write about the waterfall(瀑布)they had visited.On one student’s paper was Just the one sentence,“It’s so cool.Maybe he thought it was the best way to show what he saw and felt.

But the story also shows a scarcity(缺乏)of words.Without “cool”,some people have no words to show the same meaning.So it is quite important to keep some credibility(可信性).Can you think of many other words that make your life as colourful as the word “cool”? I can.And I think they are also very cool.

小题1:We know that the word“cool”has had ________.

A.only one meaning

B.no meanings

C.many different meanings

D.the same meaning小题2:In the passage,the word“express”in second paragraph means“________”.

A.see

B.show

C.know

D.feel小题3:If you are _______ something,you may say,“It’s cool.”

A.interested in

B.angry about

C.afraid of

D.unhappy with小题4:The writer takes an example to show he is ________ the way the word is used.

A.pleased with

B.strange to

C.worried about

D.careful with小题5:In the passage,the writer suggests(暗示)that the word “cool”________.

A.can be used instead of many words

B.usually means something interesting

C.can make your life colourful

D.may not be as cool as it seems

单项选择题