共查询到20条相似文献,搜索用时 93 毫秒
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用演示电表显示弹性形变唐金安(河南安阳县崔家桥乡一中455112)新编初中物理教材"动能和势能的转化"中安排了一个演示动能和弹性势能相互转化的实验.实验时用小球撞击弹簧片使之发生形变,而后弹簧片复原将球弹回,从而说明动能和弹性势能的相互转化.实验不足... 相似文献
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力学问题中常见的势能是弹性势能和重力势能.由于势能的相对性,在选取不同的势能零点位置时,计算过程有简有繁.因而,确定合适的势能零点会给解决问题带来方便. 相似文献
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弹性势能差值不会因为弹性势能的零点选择而改变,但当规定弹性势能的零点位置不同时,系统的弹性势能却有不同的表达式.当选择弹簧原长时为零势能点,弹性势能的表示形式最简单,Ep=1/2kx2.是不是通常情况都是以弹簧原长时为零势能点?在具体问题中,零势能点的选取有没有特定的要求?文中对上述问题作出了系统性的分析与回答. 相似文献
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为了研究低速高电荷态离子在C60薄膜中引起的势效应,用能量为200keV的高电荷态Xen+(n=3,10,13,15,17,20,22,23)离子辐照了C60薄膜。用原子力显微镜(AFM)和Raman散射技术分析了辐照过程中高电荷态Xen+离子所储存势能在C60薄膜中引起的效应,即势效应。AFM分析结果表明,辐照C60薄膜的表面粗糙度随辐照Xen+离子电荷态(即势能)的增加而减小,揭示了势效应的存在。而Raman分析结果表明,由于Xe离子的动能远大于其所储存的势能,因此,尽管有表面势效应的影响,但在Raman分析的深度范围内,弹性碰撞还是主导了C60薄膜的损伤过程。 相似文献
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对如何选择典型过程,让弹性势能为零或者弹性势能等量替代的方法作了一些分析与探讨,让学生了解了弹簧题的特点和解题技巧. 相似文献
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拟合在对称性匹配微扰理论(SAPT)水平下精确计算的HF分子在3个不同核间距时的相互作用能,获得了He–HF复合物的解析振转势能面;这个势能面与现有的理论势符合得很好.在此势能面上,使用密耦近似计算了He–HF碰撞能量从160 cm –1 到694 cm –1 范围内的分波截面,并采用半经典方法详细讨论了长程吸引和短程各向异性相互作用对弹性和非弹性分波截面的影响. 相似文献
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Global Weak Solutions of the Boltzmann Equation 总被引:1,自引:0,他引:1
Carlo Cercignani 《Journal of statistical physics》2005,118(1-2):333-342
A new definition of the concept of weak solution of the nonlinear Boltzmann equation is introduced. It is proved that, without any truncation on the collision kernel, the Boltzmann equation in the one-dimensional case has a global weak solution in this sense. Global conservation of energy follows. 相似文献
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Carlo Cercignani 《Journal of statistical physics》2006,123(4):753-762
The definition of the concept of weak solution of the nonlinear Boltzmann equation, recently introduced by the author, is used to prove that, without any cutoff in the collision kernel, the Boltzmann equation for Maxwell molecules in the one-dimensional case has a global weak solution in this sense. Global conservation of energy follows. 相似文献
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The definition of temperature in non-equilibrium situations is among the most controversial questions in thermodynamics and statistical physics. In this paper, by considering two numerical experiments simulating charge and phonon transport in graphene, two different definitions of local lattice temperature are investigated: one based on the properties of the phonon–phonon collision operator, and the other based on energy Lagrange multipliers. The results indicate that the first one can be interpreted as a measure of how fast the system is trying to approach the local equilibrium, while the second one as the local equilibrium lattice temperature. We also provide the explicit expression of the macroscopic entropy density for the system of phonons, by which we theoretically explain the approach of the system toward equilibrium and characterize the nature of the equilibria, in the spatially homogeneous case. 相似文献
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为了精准快速地计算微波器件中微放电效应的阈值,在传统蒙特卡罗方法的基础上,提出了三种不同的蒙特卡罗方法,分别对二次电子的初始能量、出射角度和初始相位等参数进行随机,结合四阶龙格-库塔法和Furman模型计算电子的运动轨迹和单次碰撞产生的二次电子发射系数,然后应用不同的方法计算有效二次电子发射系数作为微放电效应的判据.以平板传输线TEM模式为研究对象,采用四种不同的蒙特卡罗方法计算微放电阈值,并与统计模型结果进行对比.结果表明单电子-多碰撞蒙特卡罗方法误差最小,而且稳定性最好. 相似文献
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D. Buchholz 《Communications in Mathematical Physics》1975,45(1):1-8
Within the framework of local relativistic quantum theory in two space-time dimensions, we develop a collision theory for waves (the set of vectors corresponding to the eigenvalue zero of the mass operator). Since among these vectors there need not be one-particle states, the asymptotic Hilbert spaces do not in general have Fock structure. However, the definition and “physical interpretation” of anS-matrix is still possible. We show that thisS-matrix is trivial if the correlations between localized operators vanish at large timelike distances. 相似文献
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Weiping Yao Songbai Chen Changqing Liu Jiliang Jing 《The European Physical Journal C - Particles and Fields》2012,72(2):1898
We study the collision of two geodesic particles in the accelerating and rotating black hole spacetime and probe the effects
of the acceleration of black hole on the center-of-mass energy of the colliding particles and on the high-velocity collision
belts. We find that the dependence of the center-of-mass energy on the acceleration in the near event-horizon collision is
different from that in the near acceleration-horizon case. Moreover, the presence of the acceleration changes the shape and
position of the high-velocity collision belts. Our results show that the acceleration of black holes brings about richer physics
for the collision of particles. 相似文献
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The collision efficiency of spherical dioctyl phthalate aerosol particles in the Brownian coagulation 下载免费PDF全文
The collision efficiency in the Brownian coagulation is investigated. A new mechanical model of collision between two identical spherical particles is proposed, and a set of corresponding collision equations is established. The equations are solved numerically, thereby obtaining the collision efficiency for the monodisperse dioctyl phthalate spherical aerosols with diameters ranging from 100 to 760 nm in the presence of van der Waals force and the elastic deformation force. The calculated collision efficiency, in agreement with the experimental data qualitatively, decreases with the increase of particle diameter except a small peak appearing in the particles with a diameter of 510 nm. The results show that the interparticle elastic deformation force cannot be neglected in the computation of particle Brownian coagulation. Finally, a set of new expressions relating collision efficiency to particle diameter is established. 相似文献
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The forward scattering of radiation by multicomponent systems is expressed in terms of the chemical potentials and of the collision lengths associated with the components.Contrast lengths can be defined in various unequivalent ways. The formula giving the scattering cross section in terms of such contrasts is derived geometrically. This approach allows a discussion concerning the best definition of the contrast lengths. 相似文献
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We study the collision of two orthogonally polarized and equal-amplitude vector solitons in the nonintegrable coupled nonlinear Schrodinger equations. We show that the separation velocity versus collision velocity graph has a fractal structure. When we zoom into this graph, we get a structure qualitatively identical to the original one. In addition, collision dynamics in the zoomed-in windows is intimately related to that in the original graph. We explain this fractal dependence of the collision by a resonance mechanism between the translational motion of vector solitons and internal oscillations inside a vector soliton. 相似文献