问题 问答题

如图甲所示,用面积为S的活塞在汽缸内封闭着一定质量的空气,活塞上放一砝码,活塞和砝码的总质量为m,现对汽缸缓缓加热使汽缸内的空气温度从TI升高到T2,且空气柱的高度增加了△l,已知加热时气体吸收的热量为Q,外界大气压强为p0,问此过程中被封闭气体的内能变化了多少?请在下面的图乙的V-T图上大致作出该过程的图象(包括在图象上标出过程的方向).

答案

由受力分析和做功分析知,在气体缓缓膨胀过程中,活塞与砝码的压力对气体做负功,大气压力也对气体做负功;

外界对气体所做的功W=-mg△l-p0S△l;

根据热力学第一定律得:△U=W+Q=-mg△l-p0S△l+Q;

气体做等压变化,则体积随热力学温度成正比变化,V-T图所图所示:

阅读理解

阅读与表达。

     Jan Mela isn't like most kids. Two years ago, he lost an arm and a leg. But that didn't stop him.

     On Saturday, the 15-year-old boy from Poland walked to the North Pole without any help.

     "If I can do it, other people can do great things, too." Mela said before he went.

Polish newspapers said Mela was the youngest person and the first handicapped (残疾的) person to walk

to the North Pole.

     How did Mela lose an arm and a leg? He had an electrical accident. Now he walks with the help of a

62,000-yuan man-made leg.

     After the accident, Mela felt sad for himself. But he didn't lose hope. One day, he met Marek

Knminski, a Polish explorer. Eight years ago, Kaminski went to the North Pole and the South Pole in the

same year. Mela wanted to see the Noth Pole, too. So Mela asked Kaminski if they could go together

next time.

Kaminski said yes!

     It took Mela 21 days to get to the Noth Pole. The last three or four days were really hard because of

bad weather. But Mela kept doing.

     "I didn't think we would make it," he said. "Then, things got better."

1. What does the underlined word "that" refer to?

    ____________________________________________________________________

2. Why did Polish newspapers report the travel to the Noth Pole?

    ____________________________________________________________________

3. How does Mela walk after the accident?

    ____________________________________________________________________

4. Where did Kaminski go eight years ago?

    ____________________________________________________________________

5. Why did Mela make the travel?

    ____________________________________________________________________

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