The transverse wave of the spring longitudinal wave and the conditions of the performance of Liu Yuqin Shandong University of Technology Jinan 250061 spring longitudinal wave performance.
Many physics textbooks often introduce such a simulation experiment, suspending the deceleration light spring horizontally, and 3 pushing the end of the spring continuously, there is a sparse part of the coil and the dense part of the transmission along the axis direction, 1 it is intuitive and concise The main performance of the longitudinal wave is called the spring longitudinal wave.
However, when carefully studied, the formation mechanism of the spring longitudinal wave is found to be substantially different from the longitudinal wave or air sound wave propagating in the thin rod. When the horizontal spring of the horizontal suspension is pulled, the displacement is perpendicular to the wire which is exactly the vertical coil, and the shear occurs between the adjacent sections of the spring wire. The wave associated with the shear is the transverse wave, which propagates along the spiral wire of the spring.
Since the transverse wave propagates along the coil, the vibration direction of each particle is just parallel to the axis, so the dense wave of the coil that propagates along the axis is observed during the performance. To illustrate this, it is assumed that a plurality of coils are included in the length of the transverse wave. At any time, the mass points of the same mass have different vibration phases, so there are different displacement distributions, but the displacement distribution Spatially periodic changes. If the particle point in the 14-wavelength range on the left side of the point is the same as the particle point displacement in the 14-wave radius on the right side, the coil around the 4 point is close to the dense part; for example, the frame is adjacent to the point. It is also at the point of equilibrium. The particle point within the 14-wavelength of the left point of the force point is opposite to the particle point displacement within the 14-wavelength range on the right side, and the coil around the 5 point is sparsely dispersed. In this way, since the transverse wave propagates along the spiral wire of the spring, the sparse portion and the dense portion of the spring ring are correspondingly advanced in the axial direction, which forms the longitudinal wave of the spring.
The following is an analysis of how the wave velocity and wavelength of the longitudinal wave of the spring are determined. Let the radius of the torsion spring be Han, and the distance between the 嫘 为 æ›° æ›° æ›° æ›° æ›° æ›° æ›° æ›° æ›° æ›° æ›° åŒ åŒ åŒ åŒ åŒ åŒ åŒ åŒ åŒ åŒ åŒ åŒ åŒ åŒ åŒ åŒ åŒ åŒ åŒ åŒ åŒ åŒ åŒ åŒ åŒ åŒ åŒ åŒ åŒ åŒThe wave velocity of the transverse wave is determined by the shear modulus 6 of the material and the mass density, and has the following relationship: The wave velocity of the spring longitudinal wave is determined by the shear modulus and mass density of the radius pitch material of the coil spring.
If the frequency of the pull-pull spring is the wavelength of the longitudinal wave of the wavelength that can be obtained, the wavelength of the longitudinal wave of the spring is seven 7 (1). It can be seen from the formula 6 and the equation, such as the longitudinal wave of the spring. However, if the pulling frequency is too high, it will only contain a few turns of the coil in the wavelength range of the transverse wave. At this time, the sparsely dense wave is not obvious enough. If the frequency is again, it is assumed that exactly =VZnR1+, then each The phase difference between the corresponding mass points of the adjacent elastic circle is 2, and these mass points always have the same displacement, while the non-interstitial points in the same ridge have different sparse waves. Therefore, to successfully perform the spring longitudinal wave, pull The frequency of the spring should be appropriate.
Based on the above analysis, the following conclusions are drawn: When the end of the revolving spring is pulled, the adjacent section of the spring wire is sheared, and a transverse wave propagating along the cage is generated. The propagation of the sparula and the dense portion along the axis is caused by the transverse wave or the accompanying phenomenon. In short, the transverse wave is the essence, and the spring longitudinal wave is present.
References 1 Cheng Shoumo, Jiang Zhiyong. General Physics Booklet. Independence education book. Science Press 1980.594 is connected to the 38-page external method. The uncertainty formula of the 2.2-volt double-ampere method is not necessary to measure and only can be calculated directly according to the 3 or 4 formula. The type can be related to the heart and the team, so the 7 and 8 types are larger in size; while the 9th type has nothing to do with the heart, so the 9 type, smaller, 3 single volt double-ampere measuring resistance The experiment focuses on the ratio of the measured values ​​directly to the two measured values, that is, it directly reflects the essence of the Ohm's law experiment and makes the experimental principle more concise.
2 The experimental method is simple, it is not necessary to select the line connection method, and it is not necessary to correct the measurement result, thereby simplifying the experimental method.
3 The measurement result is accurate. It does not absorb the power of the measured circuit of the brother branch. The current through the current and voltage does not affect the current of the circuit under test. 4 References Ding Shenxun, Zhang Kongshi. The physical real crow tutorial part of the general physics experiment. , Hua University Press, Beijing 1992.612 Li Huaping physics experiment. Higher Education Press, 1988.128
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