问题 探究题

物体尺在重力作用下由静止开始下落的运动称为“自由落体运动”.小明对这种落体运动产生了探究的兴趣,提出 如下两个问题,问题一:物体下落的快慢是否与物体的质量有关?问题二:物体下落的高度与下落的时间存在着怎样的关系? 于是他找来一些器材并在可忽略空气阻力情况下准备进行实验.

(1)请你帮助小明设计探究“问题一”的实验方案;

(2)小明探究“问题二”时,通过实验,测量出同一物体分别从最高点下落的高度为h1、h2、h3,并测量出每次下落的高度所对应的下落时间为t1、t2、t3…,分析实验数据发现:“物体下落的高度与下落的时间不满足正比例关系”,他猜想 “物体下落的高度与下落的时间平方成正比”,若要验证这一猜想,应如何处理分析实验数据?

答案

(1)选用质量不同的物体,比较它们下落相同的高度所用的时间。(或选用质量不同的物体,比较它们在相同时间内下落的高度);

 (2)计算出下落的高度与对应下落的时间平方的比值,即:…如果它们的比值在误差范围内可认为相等,说明以上猜想是正确的,否则猜想是错误的。

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     Tim was ten years old. He was not a very good pupil, and he did not like  1  to do homework
because he enjoyed  2  other things in his free time. Frequently he did not do his
homework and when he did do it he always  3  a lot of mistakes.
     One day his mathematics teacher  4 Tim's homework and saw that he  5  all his
sums right. He was very pleased and rather  6 . He called Time to his desk and said to him.
"You got all your homework right this time, Tim. What  7 ? Did you father help  8  ?"
     Usually Tim's father did help him  9  his homework, but the evening before this, he had not
been able to, because he had not been at home, so Tim answered, "No, sir, he was very busy last night,
so I had to do it all  10  ."
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