作者gary85238 (小黄)
看板Physics
标题[题目] 推甄题目2题
时间Sat Oct 8 14:08:15 2011
[领域] 热力学 与 力学 (题目相关领域)
[来源] 硕士推甄试题 (课本习题、考古题、参考书...)
[题目]
1.
The gravitational force between two particles with masses m and M ,
initially at rest at great seperation , pulls them together . Show that
at any instant the speed of either particle relative to the other ,
d is their separation at that instant .
2. You have 1 mole of helium gas and 2 mole of neon gas in two containers with
same temperature and pressure . After you mix them together with the
same fixed temperature and pressure , the increase of the system entropy
is _____ R , where R stands for the universal gas constant .
[瓶颈] (写写自己的想法，方便大家为你解答)
0.5 0.5
1. 我相对速度是把两个的速度相加，算出[G(M+m)/d] ，但是答案是[2G(M+m)/d]
不知道哪边观念错了...
2. 混合後的压力、温度同，体积不是也相同?? 看不太懂题目的意思
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※ 发信站: 批踢踢实业坊(ptt.cc)
◆ From: 1.175.129.130
1F：→ eldar:1.能量: 0=-GMm/d +(p^2)/2M+(p^2)/2m; 动量 p=mv=MV;A: v+V 10/08 14:49
2F：推 qna:能量: 0=-GMm/d +0.5μVr^2 .. Vr = [2G(M+m)/d]^0.5 10/08 18:22
3F：→ k1220790108:112? 10/08 23:35
4F：推 ryoma3016:第二题 ds= [n*R*ln(V2/V1)]= [1*ln(3)+2*ln(3/2)]*R 10/09 21:51
5F：嘘 pp2009:第一题的英文好烂, 不知道在问啥. 10/11 09:34
6F：→ chungweitw:哈. 第一题英文的确乱七八糟 10/11 12:36
7F：→ gary85238:用不着嘘吧....题目就是这样写= = 10/14 08:57
8F：→ pp2009:抱歉, 那个嘘想嘘的是题目本身, 不是 po 版的人. 10/15 23:52
9F：推 Frobenius:帮推回来 10/15 23:53