用台式扭摆测量转动惯量

一前言 转动惯量是刚体转动过程中惯性大小的量度,是工程设计中常需知道的重要物理量,规则物体绕定轴的转动惯量可以通过数字运算求出,而对不规则物体用计算法计算则往往很困难并且不易算准.因此,测量转动惯量的实际意义并不在于对规则物体的测量,而是在于对不规则物体的测量. 目前,用来测量转动惯量的常用仪器是三线摆,它并不适用于测量不规则物体的转动惯量.因为,当不规则物体放在摆盘上时,造成三线摆的“三线”承受张力不同,破坏了推导三线摆测量转动惯量计算公式的适用条件.在这种情况下,待测物体的转动惯量不能再用公式 进行计算. 而用…     

基于PASCO转动运动传感器测量刚体转动惯量

PASCO转动运动传感器可以精准地测量并实时地记录物体转动时的角速度。在落体法测量刚体转动惯量的实验中，为了提高实验的精度，将PASCO转动运动传感器与刚体转动惯量实验仪相结合，用PASCO转动运动传感器直接测量角速度并计算角加速度。改进后的仪器简化了实验步骤，提高了实验精度。对圆盘、圆环和圆柱试样的转动惯量进行测量，三组实验的相对误差分别为0.2%、0.7%和0.3%,实验结果准确。通过实验结果可得，改进后的实验仪器操作简单且测量精度很高。     

不同线长高度测量圆盘转动惯量产生误差的研究

实验中由三线摆法测定物体的转动惯量,现在采用累积放大法测量周期,用平均法计算周期,来研究不同线长高度下测量圆盘转动惯量产生误差的影响。并分析圆盘转动惯量测量值与理论值的百分差与线长高度之间的关系。最后得出实验结果,发现线长高度越小,物体的转动惯量测量误差越大,当高度为50 cm时,物体的转动惯量测量误差最小。     

关于“用转动惯量仪测物体转动惯量”实验的疑问

用转动惯量仪测量物体转动惯量,是普通物理实验中,最简单的一种测转动惯量方法.这里所说的是圆盘状物体对其中心轴的转动惯量.(参见人民教育出版社1981年出版的华中工学院、天津大学、上海交大编《物理实验》).它的原理和操作简单、现象直     

测量不同质量圆盘下圆盘的转动惯量误差的研究

实验由三线摆法测量物体的转动惯量,现在采用累积放大法测量周期,用平均值计算周期,分析圆盘转动惯量测量值及理论值的百分差与下圆盘质量之间的关系,从而来研究一定高度不同质量圆盘下圆盘转动惯量产生的误差影响。最后得出实验结果,下圆盘质量越小,误差越小,当下圆盘质量小于0.085kg时,误差突然增大。     

同轴带电刚体转动惯量与磁矩的大小比较

本文给出并证明了电荷和质量分布相同的刚体绕相同轴转动时的转动惯量与磁矩的大小之间的特定比例关系;在此基础上,给出并证明了带电刚体磁矩的平行轴定理和垂直轴定理.这些结论将大大简化求解带电刚体转动时具有的磁矩问题.利用这一关系可以帮助教学.     

在不同转角下测量圆盘的转动惯量产生误差的研究

由于实验用三线摆法测定物体转动惯量的转角较大,但是理论推出的转角一般控制在5度以内,故现采用投影法和平均值计算转角的方法来研究在不同转角下测量圆盘的转动惯量产生的误差,并分析圆盘转动惯量测量值与理论值的百分差与转角之间的关系,最后得出圆盘转动惯量测量值与理论值的百分差随转角变化成二次曲线。     

双悬扭摆测量转动惯量及平行轴定理的实验研究

转动惯量是描述刚体转动惯性量度的重要物理量, 它具有重要的物理意义. 本文利用一种双悬扭摆的 实验装置来对物体的转动惯量进行实验研究以及对平行轴定理进行实验验证     

匀角速转动带电薄圆盘产生的磁场分布计算与讨论

在球坐标系中,通过求解多个区域的拉普拉斯方程,得到匀角速转动带电薄圆盘产生的标量磁位和磁场分布,进而给出转动薄圆盘的中心、中心轴线上、近区和远区的磁场.     

对几种不常见刚体转动惯量的研究

对于常见刚体,如均匀细棒,圆盘,圆环,圆柱等,其转动惯量的推导和计算结果在各种大学物理教科书中已有陈述,本文将对一些不常见形状刚体的转动惯量,从理论上进行一个详细的研究,计算它们的转动惯量.     

Dissipative Cylindrical Collapse of Charged Anisotropic Fluid

We have studied the dynamics of a cylindrical column of anisotropic, charged fluid which is experiencing dissipation in the form of heat flow, free-streaming radiation, and shearing viscosity, undergoing gravitational collapse. We calculate the Einstein-Maxwell field equations and, using the Darmois junction conditions, match the interior non-static cylindrically symmetric space-time with the exterior anisotropic, charged, cylindrically symmetric space-time. The behavior of the density, pressure and luminosity of the collapsing matter has been analyzed. From the dynamical equations, the effect of charge and dissipative quantities over the cylindrical collapse are studied. Finally, we have derived the solutions for the collapsing matter which is valid during the later stages of collapse and have discussed the significance from a physical standpoint.     

A Toy Model for Magnetic Field Configurations in Black Hole Accretion Discs

We discuss the feature of the magnetic field configuration arising from double counter oriented electric currentrings in the accretion disc around a Kerr black hole （BH）. We discuss the relevant physical quantities corresponding to this configuration： （1） the power and torque transferred by the large-scale magnetic field, （2） the angular momentum and energy fluxes transferred from the BIt to the inner disc, （3） the radiation flux from the disc. In addition, we discuss the possibility that the closed magnetic field anchored at the disc probably evolves to the open magnetic field, which is helpful to produce the jet from the disc.     

Distribution of electric potential in oil film on water surface induced by charged disc in water

Charged disc-shaped objects are parts of many colloidal systems, as well as a model of discretely charged interfaces. An analytical expression for the distribution of electric potential inside dielectric wetting film between diluted electrolyte and dielectric media caused by a charged disc inside electrolyte was derived within the Debye–Hückel approximation with consideration of effects of boundary polarization. The accuracy and convergence of the expressions at different distances from the disc were analyzed. A comparison with point charge potential was discussed.     

稀土区对关联经验参数公式的研究

在相对论平均场理论框架下， 采用不同对关联的参数公式对Ce, Gd和Yb稀土区同位素链进行了计算和研究。 理论计算表明: 尽管采用能隙经验参数公式和对力强度经验参数公式在能否表现出原子核的壳结构上有所区别， 但具体计算的其它物理量（如结合能、 双中子分离能等）趋向一致， 都能很好地反映原子核的基态性质。 In the framework of relativistic mean field (RMF)theory， we use BCS approximation to calculate Ce， Gd and Yb isotopic chains with different pairing parameters. And found whether they can show shell structure are different， but other physical quantities are similar by using different kinds of pairing parameters， both can correctly reproduce the experimental binding energies， two neutron separation energy and potential curves.     

Effects of a finite number of particles on the thermodynamic properties of a harmonically trapped ideal charged Bose gas in a constant magnetic field

We investigate the thermodynamic properties of an ideal charged Bose gas confined in an anisotropic harmonic potential and a constant magnetic field. Using an accurate density of states, we calculate analytically the thermodynamic potential and consequently various intriguing thermodynamic properties, including the Bose–Einstein transition temperature, the specific heat, magnetization, and the corrections to these quantities due to the finite number of particles are also given explicitly. In contrast to the infinite number of particles scenarios, we show that those thermodynamic properties,particularly the Bose–Einstein transition temperature depends upon the strength of the magnetic field due to the finiteness of the particle numbers, and the collective effects of a finite number of particles become larger when the particle number decreases. Moreover, the magnetization varies with the temperature due to the finiteness of the particle number while it keeps invariant in the thermodynamic limit N →∞.     

Critical dynamics of superconductors in the charged regime

We investigate the finite temperature critical dynamics of three-dimensional superconductors in the charged regime, described by a transverse gauge field coupling to the superconducting order parameter. Assuming relaxational dynamics for both the order parameter and the gauge fields, within a dynamical renormalization group scheme, we find a new dynamic universality class characterized by a finite fixed point ratio between the transport coefficients associated with the order parameter and gauge fields, respectively. We find signatures of this universality class in various measurable physical quantities, and in the existence of a universal amplitude ratio formed by a combination of physical quantities.     

Study on information content of the 3D object's coherent imaging and hologram information redundancy

On the basis of the light field distribution of objects with coherent illumination, and the most basic physical mechanism of binocular stereoscopic vision, we calculate the information content of the light field in ‘the smallest observation window’ produced by a point source and multi-points source respectively, and ‘the smallest observation window’ means that the size of the window just satisfies the demand of binocular stereo vision. As a result, the minimum information content of the light field that the binocular stereo vision needed is acquired. Comparing the information content of hologram with that of the light field in the hologram plane, we make out the redundancy of holographic information content and point out the direction of the holographic compression.     

Stochastic motion of a charged particle in a magnetic field: II Quantum Brownian treatment

We study the quantum Brownian motion of a charged particle in the presence of a magnetic field. From the explicit solution of a quantum Langevin equation we calculate quantities such as the velocity correlation function and the mean-squared displacement. Our calculated expressions contain as special cases the motion of aclassical particle in a magnetic field and that of afree (but quantum) particle, in a dissipative environment.     

Conserved momenta of a ferromagnetic soliton

Linear and angular momenta of a soliton in a ferromagnet are commonly derived through the application of Noether’s theorem. We show that these quantities exhibit unphysical behavior: they depend on the choice of a gauge potential in the spin Lagrangian and can be made arbitrary. To resolve this problem, we exploit a similarity between the dynamics of a ferromagnetic soliton and that of a charged particle in a magnetic field. For the latter, canonical momentum is also gauge-dependent and thus unphysical; the physical momentum is the generator of magnetic translations, a symmetry combining physical translations with gauge transformations. We use this analogy to unambiguously define conserved momenta for ferromagnetic solitons. General considerations are illustrated on simple models of a domain wall in a ferromagnetic chain and of a vortex in a thin film.     

均匀带电薄圆盘的电场

通过解拉普拉斯方程导出均匀带电薄圆盘的电势和电场的级数表达式,进而讨论均匀带电薄圆盘平面内、中心轴线上和远区的电场。