※ [本文转录自 ask 看板] 作者: jason761231 (jason) 看板: ask 标题: [请问] 有关地科的几个问题 时间: Mon May 18 00:07:40 2009 先承认这是作业 只是google和知识+找很久都得不到最适合答案 所以想问板上大大 这些问题还可以用什麽关键字搜寻? 或是有哪些专版可以进一步得到相关资讯呢? 谢谢! 1.Please describe the major stages in the formation of the solar system and how it evolved to its current state. Why do astronomers believe that the solar nebula was ratating? 2.What two properties of a planet must be known in order for its average density to be determined? How are these properties determined? 3.Please explain how the differences between the inner and the outer planets have resulted in spite of their common origin. 4.Calculate the distance from the Sun where the temperature falls below the freezing points of the following common ices: (a)H2O,273K; (b)CO2,150K; (c)CH4,100K; (d)N2,70K. 5.The angular momentum of an object is proportional to the square of its size divided by the period of rotation(D^2/P). If angular momentum is conserved, then any change in size must be compensated for by a proportional change in period, so as to keep D^2 divided by P a constant. Suppose that the solar nebula gcgan with a diameter of 10,000 AU and a rotation period of 1 million years. What would be its rotation period when it had shrunk to the size of the orbit of Pluto? To the orbit of Jupiter? To the orbit of the Earth? 1.请描述太阳系初始时主要的组成状态及现在的组成状态，为什麽天文学家相信是这样？ 2.要决定一个星球的平均密度需要哪两个数值，而这两个数值又是如何测定？ 3.请解释类地及类木行星的不同，尽管他们的发源是同一个。 4.计算下列物质在距离太阳多少时会达到凝固点。 （a）H2O,273K ; (b)CO2,150K ; (c)CH4,100K ; (d)N2,70K 5.一个物体的角动量是和他的大小平方除以周期成正比，即（D^2/P），如果角动量守恒 ，那任何大小的改变也会造成周期成比例的改变，D^2除以P也将为一个常数。假设太阳云 气学说开始时半径为10,000 AU，而周期为1百万年。当大小改变如（a）冥王星 （b）木 星 （c）地球时，周期将是多少？ --

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