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问题 选择题

一颗人造地球卫星的速度等于第一宇宙速度，每昼夜绕地球转n周，地球半径为R.现欲发射一颗地球同步卫星，它应定点于赤道上空的高度是 （    ）

A．

B．

C．

D．

答案

答案：D

题目分析：由第一宇宙速度，周期为T/n，T为地球自转周期，，对地球同步卫星周期为T，则有由此可知，D对；故选D

点评：难度中等，本题用到了黄金代换、同步卫星周期公式的推导

填空题

圆的半径扩大4倍，它的面积扩大______倍，直径扩大______倍，周长扩大______倍．
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问答题

The potential of computers for increasing the control of organizations or society over their members and for invading the privacy of those members has caused considerable concern.
The privacy issue has been raised most insistently with respect to the creation and maintenance of data files that assemble information about persons from a multitude of sources. Files of this kind would be highly valuable for many kinds of economic and social research, but they are bought at too high a price if they endanger human freedom or seriously enhance the opportunities of blackmailers. (2) While such dangers should not be ignored, it should be noted that the lack of comprehensive data files has never before been the limiting barrier to the suppression of human freedom.
Making the computer the villain in the invasion of privacy or encroachment on civil liberties simply diverts attention from the real dangers. Computer data banks can and must be given the highest degree of protection from abuse. (3) But we must be careful, also, that we do not employ such crude methods of protection as to deprive our society of important data it needs to understand its own social processes and to analyze its problems.
Perhaps the most important question of all about the computer is what it has done and will do to man’s view of himself and his place in the universe. (4) The most heated attacks on the computer are not focused on its possible economic effects, its presumed destruction of job satisfaction, or its threat to privacy and liberty, but upon the claim that it causes people to be viewed, and to view themselves, as ’machines’.
What the computer and the progress in artificial intelligence challenge is an ethic that rests on man’s apartness from the rest of nature. An alternative ethic, of course, views man as a part of nature, governed by natural law, subject to the forces of gravity and the demands of his body. (5) The debate about artificial intelligence and the simulation of man’s thinking is, in considerable part, a confrontation of these two views of man’s place in the universe.
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