Table of Content

20 September 2010 Volume 29 Issue 9

  

著者文摘

The acceleration of the contact point of a rigid body rolling without sliding on the fixed surface-revisited

. 2010, 29(9):  2-2. 

Abstract ( 1293 )   PDF (255KB) ( 736 )  

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Based on the vector analysis method,the acceleration of the contact point,also the instantaneous center of rotation for a rigid body that rolls without sliding on the fixed surface,is obtained.

Vibration of a flexible rod with one end subjected to air resistance

. 2010, 29(9):  4-4. 

Abstract ( 953 )   PDF (397KB) ( 526 )  

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The vibration of a flexible rod with one fixed end and the other subjected to air resistance is studied.The boundary condition for the end with air resistance is established approximately.The eigen modes of vibration involve an exponentially decaying factor characterizing damp vibration,but are not of factorized form.Because the boundary conditions are not of Sturm-Liouville type,the theorem on the completeness and orthogonality of the eigenfunctions is not applicable. The vibration satisfying arbitrarily given initial conditions is found by the method of Laplace transform.

Discussion on boundary conditions of some complex electrostatic field and magnetostatic field

. 2010, 29(9):  8-8. 

Abstract ( 1052 )   PDF (361KB) ( 598 )  

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By solving the boundary conditions of several complex electrostatic and magnetostatic fields,we discuss a general way of solving boundary conditions of complex electrostatic and magnetostatic fields,and analyze the conclusions of some relevant electrostatic field and magnetostatic field boundary conditions in some electrodynamics textbooks on the current.

Investigation on server thermodynamic systems by statistical distribution of completely open systems

. 2010, 29(9):  12-12. 

Abstract ( 666 )   PDF (315KB) ( 629 )  

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Thermodynamic functions of server systems are calculated by using statistical distrbutions of completely open system.It is seen that the present results are the same as other distributions,nevertheless,only substituted mean values are replaced for the unchanged values in other distributions.The relatively fluctuations are completely different with other distributions and are in proportion to 1,rather than 1/N.

The mass projection method of rigid body rotational inertia

. 2010, 29(9):  16-16. 

Abstract ( 1212 )   PDF (454KB) ( 1151 )  

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According to the definition of rotational inertia,the mass projection method is presented to calculate the rotational inertia.The rotational inertia of some special rigid bodies such as the hexahedron, the ellipse plate,the cylinder and the frustum cone are discussed.

The extended topic about the problem of beetle and rubber band

. 2010, 29(9):  19-19. 

Abstract ( 833 )   PDF (355KB) ( 452 )  

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The problems of beetle and air balloon,the motion of a beetle along a tensible curve and so on are discussed.

Discussion on dynamical characteristics of tent map in ternary notation

. 2010, 29(9):  21-21. 

Abstract ( 735 )   PDF (343KB) ( 287 )  

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In this paper,we apply the ternary notation method to discuss dynamical characteristic property of a tent map within xn ∈ ,when the initial value x0 takes the limited place decimals,arbitrarily repeating decimals and arbitrarily non-repeating decimals,respectively.As x0 takes different value,the end-result for tent map shows diversity： 0,-∞,and interval within the periodic orbits,as well as in interval within the chaotic orbits.

Hyperbolic geometry property of relativistic velocity space and general expression of Thomas precession

. 2010, 29(9):  24-24. 

Abstract ( 985 )   PDF (526KB) ( 654 )  

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By the line element of relativistic velocity space,the hyperbolic geometry property of the space is particularly discussed.It is proved that the gather of relativistic velocity constitutes Klein-Beltrami model of hyperbolic geometry.General expression of Thomas precession is directly derived.It is indicated that the Thomas precession is the direct evidence of hyperbolic geometric property of relativistic velocity space.In comparison with Poincare model of hyperbolic geometry,the Klein-Beltrami model can directly explain the laws of relativistic velocity,because the coordinates in the model is usual velocity.

Discussion on the Compton effect

. 2010, 29(9):  30-30. 

Abstract ( 978 )   PDF (303KB) ( 1348 )  

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The Compton scattering and its physical explanation are illustrated in detail in this paper.According to the photon and the difference between the Compton effect and the photoelectric effect,the questions and the misunderstandings of Compton effect from undergraduates are presented and clarified.The intrinsic interaction between the photon and the electron is indicated.The inverse Compton effect is also introduced.

Solution of spin state eigenvalue and eigenfunction in double electrons system

. 2010, 29(9):  33-33. 

Abstract ( 1242 )   PDF (226KB) ( 946 )  

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The eigenvalues and eigenfunctions of electron spin state in the double electrons system are solved by using the theory of the matrix direct product.The results are discussed and the consistency with usual teaching material is shown.

The measurement of mercury wavelength by ultrasonic grating

. 2010, 29(9):  40-40. 

Abstract ( 922 )   PDF (203KB) ( 433 )  

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A new simple method is proposed for light wavelength measurement.The ultrasonic diffraction spectra of mercury and He-Ne lasers through ethanol solution（97%） are analyzed.Using the He-Ne laser wavelength as the standard value,the wavelengths of yellow light,green light and blue light in mercury are calculated.The relative errors between the calculated and the standard values are 0.38%,1.0% and 0.60%,respectively

Opinions of teaching college physics to life-science students

. 2010, 29(9):  42-42. 

Abstract ( 827 )   PDF (436KB) ( 614 )  

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With the intercrossing of life science and physical science,it is necessary to combine the physical rules with life-science problems in college physics course for life-science students.We use the equipartition of energy and knowledge of entropy and free energy to solve life-science problems in college physics course.

The coupled oscillation of magnetic needles in geomagnetic field

. 2010, 29(9):  45-45. 

Abstract ( 1269 )   PDF (513KB) ( 476 )  

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The physical characteristics of the oscillation can be predicted by building two models under different conditions.Three typical modes of oscillation are determined by three initial conditions and be verified by simple but complete experiments.Some related phenomena and characteristics are discussed later in order to deepen the comprehension of coupling oscillation.

A new measurement of latitude

. 2010, 29(9):  51-51. 

Abstract ( 984 )   PDF (352KB) ( 489 )  

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A method for measuring the local latitude through measuring the shadow length of one stick at 12：00 is introduced.According to the knowledge of spherical astronomy,a general formula for calculating the latitude is also introduced through measuring the shadow length,origin length of one stick and the measurement date.In addition,this formula is tested by an experiment in Xuzhou,whose result is 34.15,which is almost consistent with the standard value.Moreover,a more general formula is furthered by broadening the time from 12：00 to any other moment in a day.Finally,the deviations of this method are analyzed and revised.

The fingerprint of atoms

. 2010, 29(9):  59-59. 

Abstract ( 704 )   PDF (666KB) ( 647 )  

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In this paper,we reconstruct the process to discover the laws of atomic spectra using the modern tools,and introduce the common methods to deal with experimental data.