D I S实验探究弹簧振子系统中的机械能守恒定律

介绍一种用D I S研究机械能守恒定律的实验方法, 不仅为验证机械能守恒提出了一种新的方法 — — — 振动法, 也从物体动能、 重力势能和弹性势能三者相互转化的角度验证机械能守恒, 更全面地阐明了机械能守恒的 条件, 加深学生对机械能守恒定律的理解     

用间歇摆验证机械能守恒定律

本文利用间歇摆实验，寻找到验证机械能守恒的一种有效方法。     

浅析动量守恒定律的条件和应用

动量守恒定律，是力学中最重要的定律之一．但初学者在理解和应用这个定律时，常常遇到两个困难：系统的动量是否守恒，不会用动量守恒定律解题．     

非惯性系机械能守恒定律

从非惯性系动力学方程出发，可导出对非惯性系的动能定理，在此基础上，引进惯性力势能Ｕｈ及对非惯性系的机械能 Ｅ’＝Ｕ’＋Ｕｈ＋Ｔ’，又可导出质点对非贯性系的机械能守恒律．此守恒律用来求解某些相对运动问题极为简便．     

“机械能守恒定律”教改尝试

对人教版《物理.必修2》中关于机械能守恒的内容进行尝试性调整整合,把"机械能守恒定律"的教学从原先的先学习定律,后验证定律的传统模式,变成现在通过学生实验探究总结出机械能守恒定律的课堂模式.     

应用Flash软件研究动量守恒定律

改进了传统动量守恒实验方法,采用摆球正碰验证动量守恒,利用数码器材摄录运动过程,应用Flash软件进行数据分析,方便简捷,成功率高,误差值小.     

光电门验证机械能守恒定律的误差修正

利用光电门验证机械能守恒定律的实验中,瞬时速度测量的准确性是决定实验成功的关键.文章通过对光电计时器的计时原理深入分析,提出两种测量"有效遮光宽度"的方法,提高光电门测量瞬时速度的精确度,对光电门验证机械能守恒定律的实验进行误差修正.     

勿让课堂成为学生错误认识的源头

“ 机械能守恒”与“ 机械能不变”是两个不同的概念, 它们的内涵宽度不一样. “ 机械能守恒”中不但包 含了“ 机械能不变” , 而且包含着守恒条件和讨论守恒的必要性; “ 机械能不变”只是“ 机械能守恒”中数量关系的一 种表达, 不能作为“ 机械能守恒”的等效表述. 因此, 在物理规律的理解和学习中, 必须注意理解和挖掘物理概念、 物 理规律的表达形式跟它们的全部内涵和外延之间的区别与联系, 勿简单的处理, 让课堂成为学生错误认识的源头     

动量守恒定律和角动量守恒定律辨析

辨析了系统动量守恒和角动量守恒的适用条件, 旨在加深学生对动量守恒定律和角动量守恒定律的 理解. 以3个例题为例, 根据实际条件选择参数, 计算了系统的内力和外力的数值, 分析了系统所受合外力( 外力力 矩的矢量和) 远小于系统内力( 内力矩) 的条件. 结果表明, 只定性地根据物体的质量很小就得出物体的重力远小于 系统内力的结论是不充分的, 质量很小的物体的重力是否远小于系统的内力还取决于碰撞前物体的速度; 而外力 力矩的矢量和是否远小于内力矩不仅取决于碰撞前物体的速度, 还取决于碰撞的位置     

悬线式二维碰撞实验

提出用长摆线单摆实现在准水平面内的无摩擦运动,用摄像头记录二维碰撞过程,设计了检验二维碰撞中动量守恒和机械能守恒的教学实验.     

Conservation laws of the generalized nonlocal nonlinear Schrodinger equation

The derivations of several conservation laws of the generalized nonlocal nonlinear Schr?dinger equation are presented. These invariants are the number of particles, the momentum, the angular momentum and the Hamiltonian in the quantum mechanical analogy. The Lagrangian is also presented.     

A New Conservation Law Derived from Mei Symmetry for the System of Generalized Classical Mechanics

A new conservation theorem derived directly from Mei symmetry of the generalized classical mechanical system is presented. First, the differential equations of motion of the system are established, and the definition and criterion of Mei symmetry for the system of generalized classical mechanics are given, which are based upon the invariance of dynamical functions under infinitesimal transformations. Second, the condition under which a Mei symmetry can lead to a new conservation law is obtained and the form of the conservation law is presented. And finally, an example is given to illustrate the application of the results.     

A New Conservation Law Derived from Mei Symmetry for the System of Generalized Classical Mechanics

A new conservation theorem derived directly from Mei symmetry of the generalized classical mechanical system is presented. First, the differential equations of motion of the system are established, and the definition and criterion of Mei symmetry for the system of generalized classical mechanics are given, which are based upon the invariance of dynamical functions under irdinitesimal transformations. Second, the condition under which a Mei symmetry can lead to a new conservation law is obtained and the form of the conservation law is presented. And finadly, an example is given to illustrate the application of the results.     

力学模型和规律在"哥伦比亚"号失事原因中的运用

运用弹性碰撞、完全非弹性碰撞两种力学模型和动量守恒定律、动量定理等力学规律分析讨论了“哥伦比亚”号航天飞机失事的原因,旨在使读者对物理知识在航天器中的应用有更多的了解．     

General Covariant Conservation Law of Angular Momentum in General Relativity

The conservative Noether current corresponding to the invariance of the action of a gravitymatter system under the local Lorentz transformation can be interpreted as the angular momentum tensor of the system. The existence of superpotentials which are expressed in terms of the vierbein only makes the totd current iden ticdy conserved and the total angular momentum gauge-covariant. Two examples are given. It is shown that this conservation law of angular momentum in general relativity is reasonable.     

对一道力学习题解法的剖析

通过一道经典的力学习题的分析,考察内力的不同作用效果,指出加深理解物理规律适用条件的重要性.     

General Covariant Conservation Law of Energy-Momentum in f(R) Gravity

In the light of the local Lorentz transformations and the general Noether theorem, a new formulate of the general covariant energy-momentum conservation law in f(R) gravity is obtained, which does not depend on the coordinative choice.     

An Unbroken Axial-Vector Current Conservation Law

The mass, energy and momentum of the neutrino of a true flavor have an axial-vector nature. As a consequence, the left-handed truly neutral neutrino in an axial-vector field of emission can be converted into a right-handed one and vice versa. This predicts the unidenticality of masses, energies and momenta of neutrinos of the different components. Recognizing such a difference in masses, energies, momenta and accepting that the left-handed axial-vector neutrino and the right-handed antineutrino of true neutrality refer to long-lived C-odd leptons, and the right-handed truly neutral neutrino and the left-handed axial-vector antineutrino are of short-lived fermions of C-oddity, we would write a new CP-even Dirac equation taking into account the flavor symmetrical axial-vector mass, energy and momentum matrices. Their presence explains the spontaneous mirror symmetry violation, confirming that an axial-vector current conservation law has never violated. They reflect the availability of a mirror Minkowski space in which a neutrino is characterized by left as well as by right space-time coordinates. Therefore, it is not surprising that whatever the main purposes experiments about a quasielastic axial-vector mass say in favor of an axial-vector mirror Minkowski space-time.     

General Covariant Conservation Law of Energy-Momentum in f（R） Gravity

In the light of the local Lorentz transformations and the general Noether theorem, a new formulate of the general covariant energy-momentum conservation law in f（R） gravity is obtained, which does not depend on the coordinative choice.