孔隙率计算公式

发出白光的细线光源,长度为,竖直放置,且上端恰好在水面以下（如图3所示）.现考虑线光源,发出的靠近水面法线（图3中的虚线）的细光束经水面折射后所成的像,由于水对光有色散作用,若以L 如图，AB为一面墙，s为距地高为H的点光源。从s向右抛出一小球，最后落到B点。求：小球在墙AB上的影子刚抛出和落地时的速度v0与v1我认为v0=0;V1=sqrt（2gh）而答案上是V0=V1=aqrt（gh/2) 1728的立方根是什么? 中药很受西方人的欢迎 的英文翻译 Chinese medicine is ___ ___ people in western countries.中间填啥? 英语翻译There is growing concern amongst many natural scientists that human interventions are altering the capacity of ecosystem to provide goods and services needed for humans. 英语翻译In many cases,these are small species there is very little interest in,except maybe for fish feed or fish oil. 1、以10米每秒的速度开始做匀减速直线运动的汽车 第一秒内的位移为九米 则四秒内的位移是?2、一个做匀加速直线运动的物体 在开始时连续两个四秒的时间内分别通过的位移为24你和 64米 如图所示,放置于水平地面质量是10kg的物体,在与水平方向成37°角的斜向右上方的拉力F=100N的作用下,由静止开始沿水平地面作直线运动,物体与地面间的动摩擦因素为0.5,试求：（sin37°=0.6,cos37 汽车由静止开始运动 若要使汽车在开始运动的一小段时间内保持匀加速直线运动（汽车所收阻力不变）则A 不断增大牵引功率B 不断减小牵引功率C 保持牵引功率不变D 不能判断牵引功率怎样 高中非常简单物理题……(1)怎么划分系统,(2)怎样区分内、外力,(3)在斜面放置的木块与斜面看成整体,这个整体外力的矢量和为0吗?请大哥大姐多写点,详细点……谢了 高中简单物理题目在光滑绝缘的水平地面上放置四个相同的金属小球小球A、B、C位于等边三角形的三个顶点，D位于三角形中心。现让小球A、B、C带等量正电荷Q，D带负电荷q，使四个小球均处 英语翻译：The giraffes are eating the leaves.和There are many animals in it. 英语翻译there were many animals in the zoothere are many animals in the zoo是哪一个？ 2.6的立方根是多少 解立方根如题人站在距地面h千米的高出,能看到的最远距离d≈112根号h 上海东方明珠太空舱距地面的高度为350米,如果没有障碍物的影响,站在太空舱的人可以看到多远 以There are many inventions that have causde great changes in the word.there's a short introductionThere are many inventions that have causde great changes in the word.there's a short introduction.for example,thedigital camera was invented by开头 How many letters are there in the short 非常的急用呢.斜面高1m,倾角为30°,在斜面定点A以速度V0(0标在V右底下的喔)水平抛出一小球,小球刚好落于斜面底部B点,不计空气阻力,求小球抛出的速度V0(0标在V右下底)和小球在空中运动的时 有一处错误,请指出并改正1.l think there are too much rules in our school.2.Don't listen to music in the classroom and the hallways.3.We can't eat in the claass.4.We have to quiet in the schllo library5.Li Fei doesn't like english,too. do you like to stay at home? sure( ) i don't .why? there are many rules in my home . ( )i can't watch tv on school nights. i have to go bed by 9.30( )? 括号里填什么 There are too many rules and too (many /much) work in my factory. 连词成句①has get food grandpa he to for his ②many rules are there home at too my ③be don't noisy the in ciassroom ④we wear hat can can a in class 物理题 高中 课外的美词美句摘抄（注明出处）要一些初中课外的美词美句摘抄,记得注明出处.有了的不要。 初中课外美词、美句摘抄（注明出处）格式：美词：银蛇 蜡像 欲与.美句：山舞银蛇,原驰蜡象,欲与天公试比高.——————《沁园春·雪》 课外美词,美句摘抄(注明出处)课外美词,美句摘抄,要注明出处 要多点 课外美词美句摘抄我要二篇,要有好句,中心思想和我的感受,好的我加二十分! 英语翻译此句型中的地点名词能否用there？在此处there是不是名词? 求How do you think the transport system in our city could be improved?翻译! I still think our everything. There is no knowing 翻译下!谢谢! 你认为几年后我们的城市的污染会少吗?Do you think there ----- ----- ---- pollution in our city ----- 一个数的立方根的手工计算方法 计算：1/1+根号3+1/根号3+根号5+---1/根号9+根号11