问题 选择题

如图所示,两个底面积不同的圆柱形容器甲和乙,容器足够高,分别盛有水和酒精(ρ>ρ酒精),且两种液体对容器底部的压强相等。一定能使水对容器底部的压强大于酒精对容器底部压强的方法是                                          (    )

A 倒入相同质量的水和酒精

B 倒入相同体积的水和酒

C 抽出相同质量的水和酒精

D 抽出相同体积的水和酒精

答案

答案:C

∵甲和乙是圆柱形容器,

∴对容器底的压力:F=ps=ρghs=ρgV=mg=G;

∵S>S

对容器底的压强:p=p

∴m>m酒精

A、倒入相同质量的水和酒精,增加的压力相等,底面积左边容器的大,所以左边容器增加的压强小,会使水对容器底部的压强小于酒精对容器底部压强,不符合题意;

B、倒入相同体积的水和酒精,

∵ρ>ρ酒精

∴m>m酒精

这样可以使水对容器底的增加的压力大于酒精对容器底增加的压力,底面积左边容器的大,不好确定哪个增加的压强多,不能确定水对容器底部的压强和酒精对容器底部压强的关系,不符合题意;

C、抽出相同质量的水和酒精,减小的压力相等,底面积左边容器的大,所以左边容器减小的压强小,会使水对容器底部的压强大于酒精对容器底部压强,符合题意;

D、抽出相同体积的水和酒精,

∵ρ>ρ酒精

∴m>m酒精

这样可以使水对容器底的减小的压力大于酒精对容器底减小的压力,底面积左边容器的大,不好确定哪个减小的压强多,不能确定水对容器底部的压强和酒精对容器底部压强的关系,不符合题意;

故选C.

阅读理解

根据短文内容,回答问题。

     For most Americans, a clean glass of water is just a faucet away. But for many of the world's poorest

people, it's hard to get.

     On Wednesday, the United Nations (UN) marked World Water Day by trying to cut the number of people

without good drinking water-one billion human beings worldwide-in half. In the next ten years, the UN will

work with governments around the world to reduce the shortage.

     Without clean water nearby, many people use water _____. In India, many people bathe and wash their

clothes in rivers that are polluted by human waste.

     According to the UN, not having enough clean water and sanitation causes more than three million deaths

a year.

     "The links between water and human health are powerful," said Dr Lee Jong Wook, director-general of

the World Health Organization (WHO). "We cannot live without clean water."

     In fact, the International Federation of the Red Cross said that quick reaction after last year's Asian tsunami

had stopped disease. The agency provided clean water to nearly 500, 000 people in Indonesia and Sri Lanka

after the tsunami.

     World Water Day was first celebrated in 1993. Since then, it is celebrated each year on March 22.

1. What is the best title of the passage? (Please answer within 5 words.)

    _______________________________________________________________________________________

2. Which sentence in the passage can be replaced by this one? The quality of the water is closely connected 

    with human health.

    _______________________________________________________________________________________

3. What did the International Federation of the Red Cross do after the tsunami? And why? (Please answer

    within 30 words.)

    _______________________________________________________________________________________

4. Please fill in the blank in the third paragraph with proper words or phrases to complete the sentence. (Please

    answer within lo words.)

    _______________________________________________________________________________________

5. Translate the underlined sentence in the first paragraph into Chinese.

    _______________________________________________________________________________________

单项选择题