Table of Content

20 March 2025 Volume 44 Issue 1

  

The triumph of statistical physics andemergentism

SHI Yu

College Physics. 2025, 44(1):  1.  doi:10.16854/j.cnki.1000-0712.240554

Abstract ( 96 )   PDF (1108KB) ( 96 )  

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We introduce the achievements for which 2024 Nobel Prize in Physics was awarded，and describe the scientific background，history，current status and future，emphasizing the physical implications and biological sources，exposing the connections that were less known，including those among different disciplines and among scientists，indicating many different factors in the development of sciences. It is noted that the achievements winning this prize characterize the success of physics in understanding intelligence，and were initiative practice and triumph of statistical physics and emergentism. The future of physics will exist in various new forms.



Teaching application of comparing D′Alembert and Stokes paradox

HUA Lei-na1, 2, WANG Ruo-yu2

College Physics. 2025, 44(1):  17.  doi:10.16854/j.cnki.1000-0712.240096

Abstract ( 55 )   PDF (993KB) ( 38 )  

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D’Alembert paradox and Stokes paradox are the classical contents in fluid mechanics, which are also the confusing parts in teaching. Using a fixed sphere in a uniform flow field as an example, we present the key assumptions, governing equations, solutions of flow velocity and pressure for potential flow and low Reynolds number flow, respectively. The contours are plotted to compare the hydrodynamics of flows. The qualitative and quantitative analysis clarifies the origins of D’Alembert paradox and Stokes paradox. The combination of paradox and formula derivation could stimulate students’ interesting and further improve the understanding of theory.



Notes on the calculation of interplanar spacing using reciprocal lattice

YANG Jun

College Physics. 2025, 44(1):  23.  doi:10.16854/j.cnki.1000-0712.240182

Abstract ( 48 )   PDF (803KB) ( 36 )  

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Using the properties of reciprocal lattice，a general formula for calculating the crystal interplanar spacing is derived，which can be simplified when calculating the interplanar spacing of some crystals with special lattice constants. However，this formula cannot be directly used to calculate the interplanar spacing of complex unit cells. When the general formula derived from the reciprocal lattice properties is used to calculate the interplanar spacing of complex unit cells，either a representative crystal plane that meets the constraint conditions for the appearance of reciprocal points in that plane orientation should be considered，or the primitive cell corresponding to the complex unit cell should be found. Then，new basis vectors are constructed using the three edges of the primitive cell，and the basis vectors of the reciprocal lattice are obtained. Furthermore，the interplanar spacing of the original complex unit cell can be obtained by taking the reciprocal of the modulus length of the reciprocal basis vector with the same indices. Nevertheless，in the new basis vector system，the indices of the crystal planes marked in the original unit cell often change accordingly，which is often overlooked by students when calculating interplanar spacing，leading to incorrect results. In this paper，we first briefly describe the constraints for the appearance of reciprocal points on crystal planes of complex unit cell. Then，combining a specific example of a body-centered cubic unit cell，we present the process of calculating interplanar spacing using representative crystal planes or constructing new basis vectors，aiming to deepen students' understanding of these knowledge points through specific calculations and adopt them in practical applications.



Investigation on vertical vibration of horizontal rod under gravitation and resonant exciting

FANG Yizhong, CUI Xintu, SHEN Han, HUANG Zhencheng, FENG Raohui, LIAO Deju, PANG Xiaoning, LI Mengyu

College Physics. 2025, 44(1):  27.  doi:10.16854/j.cnki.1000-0712.240181

Abstract ( 39 )   PDF (814KB) ( 33 )  

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By using the method of eigen function expansion and separation of variables，under gravitational action，the definite problem of vertical vibration of horizontal uniform rod which one end maintain level but harmonically oscillate perpendicularly and the other end is free is solved strictly，all the natural frequencies of stable harmonic oscillation of level rod are acquired. It is also found that along with the time increasing continuously，when the frequency of vibration which act on the left end approach to the value of natural frequency of level rod，the rod will resonate which the nodes and wave loops are appeared. The resonant frequency and the place distribution of nodes and antinodes distinguishedly agree to the results of level rod while the left end is clamped and the right end is cantilevered，which is independent to the gravity action. It is indicated when the resonance happens，the place of left end of rod where the vibration source at can be regarded as wave node，which is acquiesced by the existing experiment. At last，the fruit of initial value problem in the process of solving is verified by Laplace transformation method.



From Fibonacci sequence to golden spirals

YANG Shijie

College Physics. 2025, 44(1):  34.  doi:10.16854/j.cnki.1000-0712.240271

Abstract ( 42 )   PDF (788KB) ( 37 )  

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This paper starts from the Fibonacci sequence to obtain a smooth oscillating Fibonacci function. The function is extended to complex plane via analytical continuation. We find that all the zeros of the function lie on a line. The Fibonacci function map strait lines on the complex plane to golden spirals, which exhibits self-similarity characteristics. We further extend the metal ratios to define metal functions and preliminarily explore their properties.






A new approach toanalysis of coupled oscillatory loop 

LIU Jinglun

College Physics. 2025, 44(1):  38.  doi:10.16854/j.cnki.1000-0712.240203

Abstract ( 46 )   PDF (829KB) ( 37 )  

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 An analysis of the coupling circuit is conducted based on the dual properties of inductance and capacitance. This analysis introduces a novel method for defining the coupling coefficient in the capacitive coupling circuits, enabling a more straightforward calculation of the coupling coefficient. Similarly, by applying the dual method, the transfer function is examined, resulting in a perfectly symmetric form. This method offers a new approach to research and teaching coupled oscillation circuits.



Investigation on teaching of conservation of momentum law by introduing optical pulling force 

CAO Yongyin, ZHOU Keya, REN Yanyu, DING Weiqiang, ZHANG Yu

College Physics. 2025, 44(1):  42.  doi:10.16854/j.cnki.1000-0712.240266

Abstract ( 48 )   PDF (802KB) ( 23 )  

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Students already learned about the law of conservation of momentum in middle school. How to reflect the advancement, innovation and challenging in college physics teaching, and how to make students feel more fresh and deep cognition are the matters that teachers need to ponder. This paper attempts to integrate the study of optical pulling force into the teaching of the law of conservation of momentum, and through the discussion of the physical mechanism that generates optical pulling force, demonstrates how to introduce cutting-edge scientific research into university physics teaching, so as to improve the advancement, innovation and challenging of the teaching, and stimulate students' learning interest and in-depth understanding of basic knowledge.



Investigations on the variable mass problems  in physics teaching and scientific research 

LIU He, CHU Pengcheng

College Physics. 2025, 44(1):  45.  doi:10.16854/j.cnki.1000-0712.240221

Abstract ( 47 )   PDF (791KB) ( 36 )  

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We investigate the variable mass problem in the undergraduate physics teaching and nuclear physics. The falling chain problems and relativistic mass are involved by considering the derivation of the elementary work. Moreover, we also discuss the properties of the equivalent quark mass in the nuclear physics teaching and compact star physics research. Our results indicate that considering the variable equivalent quark mass can significantly influence the equation of state of quark star matter and the maximum mass of quark stars.



Simulations on the temperature dependence of selfdiffusion cross section of simple gases

L Yongjun, LI Jungang, LIU Peng

College Physics. 2025, 44(1):  49.  doi:10.16854/j.cnki.1000-0712.240194

Abstract ( 36 )   PDF (1119KB) ( 25 )  

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The transport properties of gases are closely related to the collision process between molecules, and in particular, the cross sections significantly affect diffusion coefficient, viscosity and thermal conductivity. This work studies the diffusion coefficients of He, Ar, N2 and CH4 as well as their temperature dependence using molecular dynamics simulations. Based on the classical scattering model of simple gases combing with the simulation results, the temperature dependence of selfdiffusion cross section and its effect on diffusion coefficient are analyzed, which is helpful for the teaching and research of transport properties of gases in the course of college physics.



Transformation of spin state caused by spatial rotation

QIN Xuming, JU Lin, ZHAO Dongqiu, ZHANG Xiwei

College Physics. 2025, 44(1):  53.  doi:10.16854/j.cnki.1000-0712.240112

Abstract ( 48 )   PDF (782KB) ( 36 )  

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When space undergoes rotation, both the projection of the spin operator along a certain direction and its eigenstate undergo transformation, but the transformed spin state should still be the eigenstate of the corresponding operator after transformation. This article uses this principle to discuss the transformation of spin state caused by spatial rotation, and obtains a transformation formula similar to the orbital wave function. Finally, the transformation formula of general angular momentum caused by spatial rotation is discussed.



Instrument refitting for measuring inertia moment based on trilinear pendulum method and its application in sports ball measurement

CAO Jun, XU Ziyuan, QI Jiacheng, JIANG Shuai

College Physics. 2025, 44(1):  53.  doi:10.16854/j.cnki.1000-0712.240047

Abstract ( 41 )   PDF (849KB) ( 19 )  

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In this article, a device for measuring inertia moment by using a threeline pendulum method is improved. On the basis of the original device，a crossbeam is installed to place a newly designed threeline pendulum. The lower disc is replaced by a thin hemispherical shell with 3D printed uniform mass distribution. The improved device can be used to measure the inertia moment of a spherical symmetric rigid body，especially for measuring the inertia moment of various sports balls. The experimental measurement of the inertia moment of a thin semispherical shell and a solid sphere are in good agreement with the theoretical values. The inertia moments of basketball，football and volleyball around the axis are measured and compared with the theoretical values when they are considered as thin spherical shells. By measuring the inertia moment of a uniform spherical shell with a certain thickness through experiments，its inner radius can be calculated and high measurement accuracy is achieved. The improved measuring device can be widely promoted in future experiments.



The mechanics behind “cats having nine lives”

ZENG Zaiping, DAI Linfang

College Physics. 2025, 44(1):  61.  doi:10.16854/j.cnki.1000-0712.240145

Abstract ( 52 )   PDF (847KB) ( 45 )  

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The saying “cats have nine lives” originated from ancient times, filled with humor, imagination, and mystery, but it actually contains certain principles of mechanics. This article organizes and explores various mechanical explanations throughout history on this issue, categorizes them into four interpretations: the limbs opening and closing theory, the tail rotating theory, the doubleaxis rotation theory, and the spine bending theory, all of which are based on conservation of angular momentum. Although these explanations have their shortcomings, overall, they provide a more scientific basis for this ancient saying. Through indepth exploration, we hope to make people realize that mechanics, as one of the earliest branches of physics, is closely related to human life, offering a scientific way for people to deeply think about and explore natural phenomena. The principles of mechanics not only explain the marvels of cats, but also remind us of the ubiquitous mysteries of science around us, looking forward to people gaining a deeper understanding and exploration of the laws of nature.



Exploration and practice based on a problem driven knowledge graph of college physics

ZHOU Keya, MENG Qingxin, CAO Yongyin, ZHANG Lingli, DING Weiqiang, REN Yanyu, HUO Lei, ZHANG Yu

College Physics. 2025, 44(1):  66.  doi:10.16854 /j.cnki.1000-0712.240241

Abstract ( 45 )   PDF (1218KB) ( 33 )  

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Knowledge graph (KG) is an important way to empower modern education using artificial intellicollege physics|digitization|online and offline blended teaching mode gence (AI) technology. A curriculum knowledge graph (CKG) can systematically reorganize teaching content, construct the interrelationships between knowledge points. As a result, it can optimize knowledge expression and make significance for curriculum construction and talent cultivation. This article constructs a CKG based on the “Basic Requirements for Teaching Physics Courses in Science and Engineering Universities” published in 2023. Three problemoriented teaching strategies are designed, and implemented towards the future application of CKG. It can provide useful inspiration for the Digitalization and Intelligence of the fundamental mathematics and physics courses in the Emerging Engineering Education (3E) perspective.



Exploration andpractice of blended teaching mode of college physics under the background of digital education

LEI Dan, SHI Shunping, ZHAO Xiaofeng, LI Xia, CHEN Xiaofeng, LIU Shuang

College Physics. 2025, 44(1):  70.  doi:10.16854/j.cnki.1000-0712.240281

Abstract ( 35 )   PDF (1146KB) ( 16 )  

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 In the context of digital construction, this paper integrates information technology with education and teaching through the university physics course, continuously exploring and practicing a blended online and offline teaching model. The teaching team adheres to a “student-centered” teaching philosophy, based on the self-developed university physics MOOC, and integrates various methods such as knowledge graphs, digital textbooks, and online intelligent examination systems. This approach builds a blended teaching reform from multiple dimensions, including course resources, teaching models, and teaching evaluations. It forms a teaching system of “online guided self-study + classroom practice + ubiquitous learning,” effectively promoting personalized and deep learning for students and fostering the joint development of teachers and students.



The open teaching in a course of two-dimensional physics

CHEN Yuxi1, 2, WU Wenbin1, 2, YUAN Xiang1, 2

College Physics. 2025, 44(1):  76.  doi:10.16854/j.cnki.1000-0712.240215

Abstract ( 30 )   PDF (917KB) ( 16 )  

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 Open teaching is a pedagogical approach centered around student development. By creating an open environment, teachers guide students in learning independently and cultivate their innovative thinking. Here, the open teaching method is applied to a course of two-dimensional physics based on four aspects: course content, teaching methods, course experiments, and course examination. To design the diversified course content, teachers integrate basic knowledge of undergraduate physical courses with cutting-edge scientific advancements and exploratory experiments. Meanwhile, the advantages of the state key laboratory are utilized to cultivate students comprehensive abilities in multiple dimensions. Application of open teaching to this course has produced a good teaching effect and paves the way for further teaching practice of open teaching in other extension courses.



The course design of college physics based on BOPPPS model

FANG Libin, LIU Xiumin

College Physics. 2025, 44(1):  82.  doi:10.16854/j.cnki.1000-0712.240216

Abstract ( 30 )   PDF (780KB) ( 17 )  

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Aiming at the problems encountered in the course of college physics teaching in military colleges, this paper applies the BOPPPS model to the course design of college physics, taking “impulse momentum theorem” as an example to carry out the teaching design. It reflectes the studentcentered teaching process, enhances the students’ enthusiasm and participation in learning, and can apply physical theory knowledge to explain practical problems and guide military training.



Exploring the incorporation of cuttingedge research content  into lessons on thermodynamics in college physics

LIU Junjie1, 2, GUO Pan1, 2, GUO Cong1, 2, BAI Lihua1

College Physics. 2025, 44(1):  85.  doi:10.16854/j.cnki.1000-0712.240106

Abstract ( 35 )   PDF (850KB) ( 23 )  

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The ‘Two characteristics and one dimension requirements’, that is, advanced, innovative and challenging, are the construction standards for undergraduate courses in the new era. College physics is a core course in science and engineering majors. The course content covers various branches of basic physics, such as force, heat, light and electricity, aiming to improve the scientific literacy of undergraduates. Building university physics courses upon the basic requirements and improving the quality of course teaching will help meet the needs of cultivating science and engineering professionals in the new era. In this article, based on the specific practice of thermodynamic courses of college physics, we discusse how to integrate cuttingedge research content to enhance the features of university physics courses being advanced, innovative and challenging and to better cultivate students scientific literacy and innovation awareness.




Study on the oscillation amplitude of rotational  symmetric rigid body released on an incline with dual contact points

TAO Zhuo, XI Shunjia, SHEN Junjie, WANG Yinlong, ZHOU Huijun, WAN Jianguo

College Physics. 2025, 44(1):  89.  doi:10.16854/j.cnki.1000-0712.240171

Abstract ( 60 )   PDF (1070KB) ( 32 )  

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A bolt-shaped object released from an inclined plane at rest could exhibit intriguing nonlinear phenomena, wherein the twist or rotation amplitude of a rigid body perpendicular to the inclined plane increases upon surpassing a critical condition. When such a rigid body is in contact with two rigid surfaces at two points in the presence of dry friction, four motion modes occur due to the rolling or slipping state at each contact point. The constraints and forces under each mode differ, leading to differences in the dynamical equations. A MATLAB program dynamically switches to the corresponding mode based on the conditions between slipping and rolling states for numerical calculations. By exploring the initial parameters within a certain range, we identify the critical points that determine the increase or decrease of amplitude during release. These critical points correlate with the inclination angle of the inclined plane, semiapex angle of the bolt, and the twist angle at initial release. We utilize a quadric surface to fit the critical points and derive the empirical function of the critical condition. The experimental results demonstrate good agreement with theoretical calculations. This example involving a bolt serves as a practical case study for teaching the analysis of slipping-rolling transitions of a rigid body under two-point contact constraints on a plane in the presence of dry friction using numerical methods.



Experimental and numerical simulation study of droplet motion driven by electrostatic induction

LUO Yongzhou, LI Ziqi, DAI Rucheng, WANG Zhongping, SUN Xiaoyu, ZHANG Zengming

College Physics. 2025, 44(1):  96.  doi:10.16854/j.cnki.1000-0712.240143

Abstract ( 40 )   PDF (906KB) ( 19 )  

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 In this paper, the drag and acceleration motions of droplets have been achieved by using electrostatic induction. By studying the velocity of the droplet motion, the friction coefficient between the droplet and the substrate is obtained as 0.008, as well as the viscous coefficient between the droplet and the surrounding is 0.028 kg/(m·s). Moreover, the electric field force on the droplet and the process of the droplet's motion are calculated by numerical simulations. At 400 V, the droplet firstly accelerates and then decelerates, and stops moving under the tip electrode. At 1000 V, the droplet accelerates dramatically and touches the tip electrode. The simulations are in good agreement with that of experiments.



Recurrence of Hertz experiment: measuring light speed using cellular wireless networks

WANG Jingbo, ZHANG Sheng, HANG ZhiHong

College Physics. 2025, 44(1):  101.  doi:10.16854/j.cnki.1000-0712.240085

Abstract ( 38 )   PDF (914KB) ( 25 )  

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Hertz successfully verified that electromagnetic waves and light have the same speed. This important experimental conclusion made electromagnetism and optics unified, and became the experimental basis of electrodynamics, which now is also one of the most important experiments in university physics. In this paper, a splitring resonator circuit under cellular wireless network is successfully designed and prepared. An accurate value of the speed of light as (3.007±0.018)×108 m/s is obtained by standing wave method, which is in good agreement with its actual value 2.998×108 m/s. In this experiment, only cellular phones and a splitring resonator circuit board (with circuit board design provided) are required, thus it can be carried out anywhere, where an identical observation method as Hertz's original experiment can be done. It may pave new road for relevant demonstrations for university and high school students.



Exploration of the motion of conduct sphere in a linear gradient magnetic field by the tensors method

SHEN Hangzheng, CAI Zhuofan, TAO Xiaoping, ZHAO Wei, PU Qirong, ZHAO Xia, ZHANG Zengming

College Physics. 2025, 44(1):  106.  doi:10.16854/j.cnki.1000-0712.230382

Abstract ( 42 )   PDF (986KB) ( 30 )  

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The second question in the 2023 China Undergraduate Physics Tournament (CUPT) “Oscillating sphere” requires the study of the motion of a surface conductive sphere in a magnetic field. Starting from the Maxwell equation system and based on the properties of good conductors, this article uses series expansion and separation of variables method to transform the problem into a Poisson equation with fixed boundaries. Then, using the spherical harmonic function under tensor expression, the force and torque of a non ferromagnetic conductive spherical shell in a uniform magnetic field and a linear gradient magnetic field are studied, and a complete differential equation describing the motion mode of the conductor spherical shell in a linear gradient field is obtained, We solved and designed experiments to explore several special solutions of the dynamic equation. Under the conditions of university physics experiments, we demonstrated the attenuation of the translational and rotational motion of the conductor ball model, as well as the coupling motion between them.



Deeply understanding self perception issues  based on experimental phenomena

HUANG Shaoshu, TAN Wen

College Physics. 2025, 44(1):  112.  doi:10.16854/j.cnki.1000-0712.240218

Abstract ( 26 )   PDF (836KB) ( 14 )  

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Using the characteristics of high self inductance coefficient of fluorescent lamp inductor ballasts and ordinary small self inductance coils, a teaching experience experiment is designed. Based on the experimental phenomena, a more in-depth study is conducted on the self inductance problem, and expressions for the self induced electromotive force and self induced current of the experimental circuit during the electrification and power-off processes in a linear model are provided.  We analyze the reasons for the incomplete agreement between the results of linear theory and experimental phenomena, and correcte the erroneous understanding of self induced current and self induced electromotive force in relevant literature.