abc≤|(a+b+c)/3|~3在物理中的应用(高一、高三)

题1 船在静水中靠风力航行.已知风速为νu,问:当船速为多大时,风时船的功率最大? 解设船速为ν,风对船的功率最大.取风柱的横截面积为S,则风对帆的冲量 Ft=ρs(ν0-ν)t(ν0-φ) ①风对船的功率 P=Fν②解①、②,得图1P=ρs(ν0-ν)2ν=1/2ρs(ν0-ν)22ν.     

活化煤和石油焦对水中氰化物的吸附特征

证实活化煤和石油焦对水中氰化物的等温吸附规律符合Langmuir方程 .活化煤的饱和吸附量Γ∞ ≈ 547mg·g-1,吸附系数K≈ 1 0 4 7× 10 -3 dm-3·mg-1;石油焦 ,Γ∞ ≈ 561mg·g-1,K≈ 9 0 17× 10 -4 dm3·mg-1.实验结果对水中氰化物的处理很有理论意义和实用价值     

对公式E=BLν的理解

在高二课本"感应电动势"一节中,课本通过E=n△ψ/△t推导出了导线切割磁感线运动时产生感应电动势大小的公式,即E=BLν.其中ν是运动速度(既可以是瞬时速度也可以是平均速度),B为磁感应强度,L为导线长度.此外此公式是在B、L、ν三者垂直的情况下导出的,因此它的使用范围是:(1)导线切割磁感线运动;(2)B、L、ν三者两两垂直.     

阶梯幼儿英语

鬟One day,Kathy and Leo mset a fox and an elephant in the woods.Ka’thy seesthe fox and says,‘'You have a small fac-e.…'You have a big face,”s。aYs the fox. , ,T;le elephant smiles‘to Lec,and says。”You have Srflall ears.”And Leo says tothe elephant.”、mu have bi(》ears.”D a d d Y,M 0 m m y,1 0 0 k a t m e.I h a v e a b i g,b i g fa c e. ,一,,_一S h O W m e y o U r S m a I I,s m a l I e a rs. @Y de a r b a b y!盎、_a ≈。?、;_荔蓑尸≥拶搿ddy和Mommy uG以和小朋友一起玩ays”的游…     

踢出个未来

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全俄中学生化学奥林匹克竞赛1993年区域级试题

X年级 理论部分试题 一、选择题 完成下列十个选择题,在你认为正确答案的字母上划圈。40分钟内完成。 1.甲基自由基带有何种电荷? a)—3 b)0 c) 1 d) 3 e)不知道 2.2-甲基戊烷有几种分子量比它小的同系物?写出它们的结构式和名称。 a)2 b)3 c)4 d)5 e)不知道 3.在标准状况下,完全燃烧1升甲烷,约需要多少升空气? a)1L b)2L c)5L d)10L e)不知道 4.苯的同系物中组成为C_8H_(10)的有几种?写出它们的结构式和名称。 a)2 b)3 c)4 d)5 e)不知道 5.二溴丙烷共有多少种同分异构体?写出它们的结构式和名称。 a)2 b)3 c)4 d)5 e)不知道     

地球质量M=5.89×10~(24)kg吗?

全日制普通高级中学教科书 (试验修订本 )《物理》第一册 (必修 )面世以来 ,得到教育界的高度评价 ,此书有利于全面推进素质教育 ,提高普通高中教育质量 .但笔者认为此书还有值得商讨之处 ,例如第 1 0 8面提供的地球质量 M=5.89× 1 0 2 4 kg,此数据可能有误 .1 979年国际大地测量和地球物理联合公布 :地球的赤道半径 ra=6 3781 37m≈ 6 .378× 1 0 6m,极半径 rb=6 356 752≈ 6 .357× 1 0 6m,扁率 e=12 98.2 57,忽略地球非球形对称 ,平均半径 r=6 .371× 1 0 6m.在赤道某海平面处重力加速度的值 ga=9.780 m/s2 ,在北极某海平面处重力加速…     

体验

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物理综合测试题

[题1] 质量相同的A、B两个小球,B位于A球正上方10米处,让B球开始自由下落的同时,使A球以初速度ν_0竖直上抛,为使两球在空中相碰并粘合在一起后,即刻向下运动,A球上抛的初速度ν_0应满足什么条件?(g=10米/秒~2)     

风力功率何时最大?(高一、高二、高三)

题一艘帆船,扬帆在河中顺风而行,当船航行的速度为多大时,风力对船做功的功率最大? 错解设风速为ν0,船航速为ν,则空气冲击帆面的速度为ν0-ν,空气流对帆面的冲击可看作弹性碰撞,碰撞前后空气流的速度变化为2(ν0—ν).设在时间t内冲击帆面的空气质量为m,对帆面的冲击力为F,由动量定理得     

Solar neutrinos

The standard solar model with the standard electroweak theory does not explain the solar neutrino problem. However, a slight modification to this theory, in which there is a mass difference in the neutrinos and mixing between them, does seem to explain the experimental observations. However to test conclusively the theory and oscillation effect, a detector which can detect separately the charged current interactions of the electron neutrinos and neutral current interaction of both the neutrinos with matter and also give accurate measurements of the two interactions is to be built. The next generation of solar neutrino experiments aims to test the above theory. One experiment, which proposes to detect neutrinos through both neutral and charged current interactions, is the Water Cherenkov Detector of the Sudbury Neutrino Observatory (SNO) at Ontario, Canada. Another Water Cherenkov Detector,the massive Super Kamiokande detector, has just become operational and the analysis of the data being collected from the detector are being reported in many conferences. The scientists at Kamiokande have very recently reported at the Neutrino ’98 Conference the exciting result that the neutrino does have a mass. They are now clear that they have reached a level of understanding in Neutrino Astrophysics, where neutrino oscillation solutions can be discussed.     

Hans Bethe, the sun and the neutrinos

We give an elementary review of recent discoveries in neutrino physics, culminating in the solution of the solar neutrino problem and the discovery of neutrino mass. Atmospheric neutrinos, reactor neutrinos and other important developments are also briefly described. G Rajasekaran is a theoretical physicist at the Institute of Mathematical Sciences, Chennai. His field of research is quantum field theory and high energy physics. Currently he is working in the area of neutrino physics.     

中微子之谜

揭开中微子之谜在物理研究中具有十分重要的作用。从中微子假说提出以来的一系列问题应予重视；太阳中微子失踪之谜，中微子质量之谜等。     

低能中微子的产生机制及应用

通过类比由爱因斯坦热辐射理论导出黑体辐射公式的方法,文章研究低能中微子辐射理论及辐射特性,进而讨论了低能中微子辐射理论的应用。结论表明,低能中微子在现实生活中非常普遍,最近在建的中微子探测器有能力探测到低能中微子的发射信号。我们预测未来几十年将是中微子研究及应用的黄金时代。     

Neutrinos and our Sun — Part 1

The elusive neutrinos have periodically yielded their secrets to man and at each such juncture major advances have been achieved in our understanding of the sub-atomic phenomena. These particles also carry invaluable information about the centre of the Sun where energy is generated through nuclear fusion. In Part I of this article, history of the discovery of neutrinos is traced, their properties and types are described. Also, the Standard Model which forms the basis of the structure of matter and of which massless neutrinos are an integral part, is described. The role of neutrinos in solar energy generation and the great ‘solar neutrino puzzle’ and its solution will be described later in the series.     

Neutrinos and our Sun — Part 3

In the concluding part of the article on Neutrinos and our Sun we discuss the detection of atmospheric neutrinos, their fluxes and zenith angle distributions. Here too one finds discrepancies with theoretical predictions. We discuss how the idea of neutrino oscillations helps resolve both the solar neutrino puzzle (discussed in Part 2) and the discrepancy observed in atmospheric neutrino fluxes. This is followed by a discussion of neutrino masses and the recent confirmation of the neutrino oscillations in the KamLAND experiment.     

Neutrinos and our sun — Part 2

In this part we describe the chain of nuclear reactions that fuse protons into helium nuclei in the centres of stars. Neutrinos play an important role in the proton-proton chain and detection of these neutrinos is important for a direct insight into the processes taking place at the centre of the sun. Experiments for the detection of solar neutrinos and the emerging result from them, known as the Solar Neutrino Puzzle, are described. The puzzle refused to go away even with very carefully designed experiments. Its solution came from physics, by reviving the idea of neutrino oscillations, speculated many decades ago. Recent experiments have confirmed these ideas and have enriched our knowledge of these fundamental particles.     

Neutrino oscillations

The 2015 Nobel Prize in Physics was awarded to two physicists-Takaaki Kajita and Arthur B McDonald, whose teams discovered that neutrinos, which come in three flavours, change from one flavour to another. This discovery is a major milestone in particle physics as it gives a clear evidence of physics beyond the Standard Model. Neutrino oscillation is a quantummechanical phenomenon whereby a neutrino created with a specific lepton flavour (electron, muon, or tau) can later be measured to have a different flavour. Historical development of the field in chronological order of experiments is briefly described in this article.     

De Broglie-Ross模型和太阳中微子问题

基于已知的 Ｄｅ Ｂｒｏｇｌｉｅ模型和 Ｒｏｓｓ模型结合的太阳中微子新模型,可以获得两个中微子合成一个光子及其能量公式。由此能解释太阳中微子的下列三个观察结果;仅检测到理论预测值的三分之一;太阳活动和中微子流间存在反相关关系并与观察到的光子释放率一致。     

中微子及中微子实验的最新成就

本文从中微子的泡利假设到实际探测到中微子的几个重要实验,全面介绍了中微子及中微子实验的最新成就。由于2002年诺贝尔物理奖获得者雷蒙特·戴维斯(RmymondDavisJr)和小柴昌俊(MasatoshiKoshiba)在中微子探测研究方面所做的卓越贡献,中微子实验所开创的中微子天文学正处在21世纪科学研究的一个前沿。