关于范氏方程修正项b的讨论

在范德瓦尔斯方程:(p+a/v~2)(v-b)=RT中,b 是方程中体积的修正项。它是对理想气体方程中体积(即分子自由活动的空间)修正而得到的。范德瓦尔斯气体分子不是质点,则每个分子自由活动的空间比气体体积要小些,应为 v-b,b 通过计算可证明它约为一摩尔气体分子总体积的四倍。关于此问题的证明许多文献上都有(见[1]、[2]),这里不再赘述,但有些文献上进一步推论:b 是一摩     

固体或液体体积与分子势能的关系

物质处于液态或固态时的分子势能是高中热学内容中的重点和难点，其大小不仅与温度和分子总数有关，还与分子间的平均距离及组成物质的分子之间的结构有关，有人认为物体受热时体积增大，分子间的平均距离变大，由于要克服分子引力做功，所以分子势能要增大；但是有些物质具有反常膨胀的性质，在反常膨张时，物体温度升高，而体积减小，分子间的平均距离减小，分子引力做正功，所以分子势能减小。     

一类旋转体体积的求法

用V=π∫baf2(x)dx可求得连续曲线y=f(x)的弧AB与直线x=a,x=b及x轴所围成的平面图形绕x轴旋转一周得到的旋转体的体积.若x轴推广为一般的直线y-yo=k(x-xo),其它条件不变,其旋转体的体积可由V=π/(1 k2)3/2∫ba[kx-kx0-f(x) y0]2|1-kf'(x)| dx求得.     

一类四棱锥体积的求解及应用

四棱锥A-BCDE中，BE∥CD，它们与面ABC所成角为a，已知BE=a，CD=b，a&;gt;b，△ABC的面积为S，求这四棱锥的体积。     

三角形面积公式S=1／2absinθ——在立几中的类比及运用

AABC中,若口、b边夹角为0,则其面积S=1/2absinθ．类比联想,可发现在立几中有一个类似此公式的三棱锥体积公式：如图1,三棱锥P—ABC中,若P—AB—C为0,     

一题七解渐现其妙

题目 在相同条件下，将盛有a体积NO和6体积NO2混合气体的容器倒置于水槽里，再向容器内缓缓通入c体积O2，容器内水面逐渐上升，最后容器内还剩余d体积气体．则a、b、c、d之间的关系为(用含a、b、c、d的等式表示)_________。     

四面体体积的教学设计

问题 已知四面体的三组对棱分别相等，且依次为a，b，c，求其体积。     

四面体的一个体积公式及其应用

三角形面积公式S△＝(1)/(2)absin C,S△＝(p(p-a)(p-b)(p-c)),其中p=(1)/(2)(a+b+c).下面,我们介绍:对于已知三条棱a,b,c及三面角A,B,C的四面体A1B1C1D1(如图1)的体积是     

巧妙的比值，你知道吗？

定理 已知△ABC三边分别为BC=a，CA=b，AB=c，分别以a、b、c为轴旋转△ABC，所得几何体体积依次为Va、Vb、Vc、则Va：Vb：Vc=bc：ca：ab．这是在课堂上师生共同发现的一个定理．略证如下：     

浅析n与N两个分子数的区别

因气体分子运动的无规则性,气体分子向各个方向运动的机会相等．一定质量的气体,单位体积的分子数为n,那么与器壁单位面积撞击的分子数为n／6．本文通过对下边两道题的解析,说明单位体积的分子数”（或与器壁单位面积撞击的分子数n／6）及单位时间内与器壁单位面积撞击的分子数N的区别．     

卡思卡特城堡

It is worthy of noting that, whilst Crookston Castle witnessed the earlier and happier portion of Mary's variegated life,     

不同的吃喝玩乐

一、吃和喝吃苹果 eat an apple, 吃药 take medicine,吃糖 have some sweets,吃饭 have one's meals,吃馆子 dine out,吃惊 be surprised/     

漏洞百出的教育

Many college freshmen arrive woefully unprepared to do college work, and as disadvantaged populations continue to grow, the share of the American work force that has made it through college is expected to plummet. Many experts blame that educational failure not just on high schools but also on colleges. School & College, a special report by The Chronicle, looks at efforts to fix the system. What reforms would better prepare students for college? What should schools and colleges be doing differently? How should state and federal officials help?     

Western and Eastern culture differences in commercial field

The communication of people partially is the communication of cultures. Culture has a direct effect on international commercial activities in all aspects. Different conceptions about time, space, equality, law and the like, lead people to deal with things in different ways. So to know cultures of the counterpart is to facil-itate our enterprises so as to have a smooth and successful communication in commercial activity.     

只要努力,不要后悔

There are numbers of crossroads on our long and unpredictable life journey where we totally have no idea about which direction to choose. No matter what our decision is, we should not turn back, but face the music and go ahead instead. I am this kind of girl who always does try without regretting, one example is how I dealt with my love.     

浅谈移民问题

Migration occurs behind a variety of reasons and has a great effect on the whole world. People may migrate in order to improve their economic situation, or in order to escape civil strife, persecution, and environmental disasters. The impact of migration is complex, bringing both benefits anddisadvantages. This paper briefly talks about the causes of migration, the allocation of benefits, and the ways in which individual countries and the international community deal with this important subject.     

风的曲线

Rosco and I wait for the fishermen to return.I sit at a wooden bench near the store at Mt.Baker Resort and watch the clouds change shape. Rosco has my belt around his neck and an eight foot tow chain hooked to a tree. Dogs must be on a leash. Ducks and rabbits are loose.     

Sister Carrie, an Adherent of Desires

Sister Carrie is one of the most controversial characters in American literature.Thought as a "fallen woman" firstly,she was defined as a "new woman" by some critics later. However, by digging into the motivaton behind the whole process of Carrie's "success", the relationship between Carrie and her creator (the author), the social conditions of then American, it can be found that Carrie has never been free-standing on her thought and she has never found her real-sdf even after becoming a famous actress. In a society dominated by mass consumerism Carrie is only an adherent of her own desires. She also is a representative of all those country girls flooded into cities, a symbol and a sacrifice of the urbanization of America in a time countryside was overcome by cities.     

Improvement of one-cycle controller by use of proportional integral differential controller

1.IntroductionOne-cyclecontrolmethod,whichwasproposedaboutonedecadeago[1],hasbecomeanattractivemethodinspecialfieldssuchaspowerfactorcorrection[2-6],switchingamplifiers[7,8],etc.Themainideaofthiscontrollerisbasedonintegrationofdiodevoltageinone-cycleandforcesittobeexactlyequaltothereferencevalue.Themainadvantageofthiscontrollerisitsrealtimeabilitytorejectthevariationofinputvoltage[1].Despitethisgreatability,ithasnogoodperformancesinrejectingofloaddisturbanceandfollowingreferencecommands.Espec…