问题 选择题

如图所示,两只完全相同的盛水容器放在磅秤上,用细线悬挂质量相同的实心铅球和铝球,(ρ)两球全部没入水中,此时容器中水面高度相同,设绳的拉力分别为T1和T2,磅秤的示数分别为F1和F2,则

A.F1=F2,T1=T2

B.F1>F2,T1<T2

C.F1=F2,T1>T2

D.F1<F2,T1>T2

答案

答案:C

题目分析:(1)对于悬吊在水中的球来说,它受到自身的重力G、水对它的浮力F和悬线对它的拉力T三个力的作用而处于平衡,则此三力间应有关系为T=G-F;以题述的铅球和铝球相比较,由于两者是质量相等的实心球,故,由于铅的密度大于铝的密度,则铅球的体积小于铝球的体积,由于两者均浸没于水中,所以铅球所受水的浮力小于铝球所受水的浮力,即,故

(2)因为液面高度相同,由P=ρgh可知,容器底受到的压强相等;又因为F=Ps,所以容器底受到的压力相等,则磅秤示数等于容器底受到的压力和容器自身的重力,故;故选C。

阅读理解

阅读理解。

     A friend of mine was fond of (喜欢) drawing a horse. He drew the horses very well, but he always

began at the tail (尾巴). Now it is the western rule to begin at the head of the horse , that is why I was

 surprised. It struck me that it could not really make any dilference whether the artist begins at the head

 or the tail or the belly (肚子) or the foot of the house, if he really knows his business. And most great

 artists who really know their business do not follow other people's rule. They make their own rules.

 Every one of them does his work in a way peculiar (奇特的) to himself, and the peculiarity means only

 that he finds it more easy to work in that way.

     Now the very same thing is true to literature (文学). And the question, "How shall I begin?" only

 means that you want to begin at the head instead of beginning at the tail or somewhere else. That is, you

 are not yet experienced (有经验的) enough to trust to your own powers. When you become more

 experienced you will never ask the question, and I think that you will often begin at the tail. that is to say,

 you will write the end of the story before you have even thought of the beginning.

1. A friend of the writer's drew the horses _____.

    A. very well

    B. in the way of western rule

    C. in the way of his own rule

    D. all of the above

2. The writer was surprised because _____.

    A. the artist began to draw at the head of the horse

    B. the artist began to draw at the tail of the horse.

    C. the artist made his own rule

    D. the artist did not follow other people's rule

3. You are not yet experienced because _____.

    A. you don't know where to begin

    B. you want to begin at the head instead of beginning at the tail

    C. you always ask the question.

    D. you do not trust to your own powers

4. When you become more experienced you will _____.

    A. never ask the question 

    B. often begin at the tail

    C. write the end of the story

    D. think of the beginning

5. The passage tells us _____.

    A.how to draw a horse

    B. how to write a story

    C. how to make our own rule

    D. to believe in our own powers

单项选择题