统计学是否呈正态分布

初二物理--力如图所示,物体甲静止在水平桌面上,当物体乙轻放在甲上后,下列现象不可能发生的是：A.甲相对于桌面保持静止状态,而乙相对于甲也静止B.甲相对于桌面保持静止状态,而乙相对 小丽家较光滑的桌面上铺着薄且较光滑的桌布,桌布上放置着两个盛水的杯子.当她快速沿水平方向将桌布从桌面抽走时,看到杯子留在原地没动.请你应用所学力学知识对上述现象简要解释 力 的试卷不求快，不求多，但求稍微有些难度 飞机在天上飞行时,它没有落向地面,则下列说法正确的是（ ）A飞机与地球没有接触,不受地球重力B飞机与地球没有接触,不受地球的吸引力C飞机对地球的吸引力大于地球对飞机的吸引力D飞机 初二物理运动和力第七章运动和力,怎么把这章学的东西分类! 学了, 力 ,力的测量,重力,同一直线上二力的合成,二力平衡,摩擦力的大小与什么有关,运动和力的关系. 把这分类 质量为8t的卡车,在水平公路上匀速行驶时受到的摩擦阻力是车重的0.02倍,求卡车行驶时,发动机对卡车的牵引力? 物体受非平衡力作用时,其运动状态是_____的.其中包括有的速度_________发生变化,有的运动_________发生变化,有的速度_________和_________同时变化. 总结运动和力的所有知识概念 重点讲下物体受力时怎样运动 出多点题目解析下 完整的 从简单到难出 复制可耻 如图30所示,体重是800N的工人利用滑轮组把浸没在水中的物体A提升出水面.物体A浸没在水中匀速上升时,滑轮组的机械效率为η1=70%.物体A被完全提出水面后匀速上升时,滑轮组的机械效率为η2=85% 体育课上,同学们在排球场上练习排球中的扣球动作,排球撞击地面的"砰、砰"声引起了小强同学的注意,地面对排球的作用力有多大呢?小强通过仔细的观察,猜想地面对排球作用力的大小可能与 在水平的两支筷子中间放上两只乒乓球,通过空心塑料管向两球间用力吹气,会发现两只乒乓球〔          〕A.  相互靠近 B.  相互远离 C.静止不动 D. 有关 力的作用是相互的 (11 12:3:55)树上熟了的苹果熟了会竖直落向地面,是因为受到了地球的吸引作用,那么反过来,地球同时是否受到苹果的吸引作用呢?为什么?如果受到,请你分析一下由于这 浮力 (14 13:33:52)连同载重共2000N的气球在竖直方向匀速下降,它受到的空气浮力为1900N,若从气球中抛掉一些重物后,气球能以同样大小的速度匀速上升,则抛掉的重物重为_____N（设气球受到的浮力 浮力、快点哈 (2 21:38:42)有一很薄的塑料袋装满水,用细线系紧后挂在弹簧测力计上称为10N,若将其浸没在水中称,弹簧测力计的示数为（）N.           为什么 初二物理的浮力怎么求,公式是F=pvg,问题是体积v怎么求,顺便帮忙区分下漂浮,悬浮时怎么求浮力.好人一生平安! 底面积为Sb的圆柱形容器内盛有适量的水,另一底面积为Sa的圆柱体A有部分体积浸在水中,当圆柱体A相对于容器下降高度为h时,水没有溢出,圆柱体A也未全部没入水中,物体A所受水的浮力增加了__ 一艘货轮的质量为8*10七次方吨,货轮的排水量为2*10八次方吨,则货轮满载是在水面匀速进行时1最大载量为多少吨2货轮满载时所受的浮力多少N（g=10N/kg） 三道初二英语选择题,在线等1.( )He is too old to run _______ to catch the bus.A,fast enough B.fastly enough C.enough fast D.enough quickly2.( )The wind blew ________ and we felt very ________.A.gentle;happy B.gently;happi 1、She is new here,so she has _____ friends at school.A.much B.Few C.little D.A little2、Help ____ to some fruits.Thank you!A.yourself B.your C.you3、I'm going to London for a holiday next month.______!A.Have a good time B.It's terrible C.Good job 第一道：Welcome ( ) home A.back B.to C.back to D.to back第二道：I have ( ) meat in the fridge .A.little ofB.a little ofC.a bitD.a bit of第三道：The teacher asked the boy many questions ,but he only answer ( ) of them .A.someB.lotsC.eachD. 1.My bike doesn't work.I will ___ this afternoon.A.make it mend B.have it mended C.have it mend D.have it to mend2.Have you ever ___ the Great Wall?A.been to B.gone to C.go to D.been3.We like those who have only one idea but make it ___.A.to work B.w 1.Air conditioners best in summerA.is sold B.sell C.would be sold D.sold away2.This radio cost me two hundredA.yuans B.yuan C.of yuan D.of yuans3.Look!The little dog is runningA.slow and slow B.more and more slowly C.more slow and more slowD.slowly a （ ）1.We saw the worker __________ in the bed in the bedroom.A.lie reading B.lies reading C.lyng to read D.lie to read( )2.Most people want to stay at home when it ________.A.is snowing B.snows C.was snowing D.snowed( )3.The accident happened ____ 初二英语语法情态动词的用法 初二英语语法选择题,最好解释The doctor ______then. A.has sent for B.was sent for C.will send for D.has been sent for A new bridge____ the river. A.built over B.was built over C.built past D.was built on 英语翻译 英语翻译The cartoon is an art form.Cartoon drawing requires lots of practice.People who draw cartoons as a profession(职业) are known as cartoonists.A cartoon is a funny picture story of a person or a situation.When one part of a person's body 英语翻译1.Russia to build its first space hotelIf you are tired of the Mediterranean and don't want to head for Disneyland again,perhaps it's time for a summer holiday in space.Russia plans to build its first space hotel,217 miles above Earth.The 英语翻译 英语翻译I think the world will be an easy place to live in.We will have machines and robots andthey will help us to do all the boring jobs and we don't have to do things like washing dished and making the beds though we won't have any dishes at a 英语翻译1Where was David( )Tim( )him this morning?A while;was looking for B while;looked for C when;looked for D why;was looking for 2He copies some articles on( )from( )every day.A the papers;newspaper B the papers;newspapers C a paper;newspaper 英语翻译he hasn't left here _____he came here A .since B.untilit is not easy to jump___the high fenceA.across,B.over