2012职称英语综合类A级之阅读理解

[职称英语的报考选择]职称英语的报考选择报考选择 1、综合类、理工类、卫生类考试如何选择？综合类文章可以考到理工类去，理工类可以考到卫生类和综合类。三类考试之间没有严格界限区分。国家在每...+阅读

2012职称英语综合类A级之阅读理解【下】

Weight on and off the Earth

We are so used to our life on the surface of the earth that it can be quite an effort for our mind to break free of all the ideas that we take for granted. Because we can feel that things are hey, we think of weight as being a fixed quality in an object, but it is not really fixed at all. If you could take a one-pound packet of butter 4, 000 miles out from the earth, it would weigh only a quarter of a pound.

Why would things weigh only a quarter as much as they do at the surface of the earth if we took them 4,000 miles out into space? The reason is this: All objects he a natural attraction for all other objects; this is called gritational attraction. But this power of attraction between two objects gets weaker as they get farther apart. When the butter was at the surface of the earth, it was 4,000 miles from the center. When we took the butter 4,000 miles out, it was 8,000 from the center, which is twice the distance. If you double the distance between two objects, their gritational attraction decreases two times two. If you treble the distance, it gets nine times weaker (three times three) and so on.

So this is one of the first things we need to remember: that the weight of an object in space is not the same as its weight on the surface of the earth. What about the weight of our pound of butter on the surface of the moon? At the distance the pull of the earth is about 4,000 times smaller than it is here on the surface, so we can fet all about the earth-pull on our butter.

On the other hand, on the moon there will be an attraction between the butter and the moon: but the butter will weigh only about one-sixth as much as it does on the earth. This is because the moon is so much smaller than the earth. The amount of gritational pull Hat a body produces depends on the amount of material in it .A packet of butter has a gritational pull of its own; but this is very small in relation to the pull of something as large as the moon, or the earth, or the sun.

41 How much would four pounds of tea weigh if it was taken 4,000 miles out from the surface of the earth?

A 1 pound.

B 2 pounds.

C 3 pounds.

D 4 pounds.

42 We find it hard to break free from ideas connected with living on the earth because___________

A it demands too great an effort for us to do so.

B we are too familiar with the way things are to question the ideas.

C we he proved that those ideas are correct.

D we are so sure of ourselves that we never doubt anything on the earth.

43 According to the passage, weight should be understood in the sense that___________

A it is fixed if it is outside the earth's gritational pull.