The method for validating the angle momentum conservation law with the linear speed

Abstract

The method of verifying the law of conservation of angular momentum with linear velocity is a new experimental method, which belongs to the invention of experimental methods, and is mainly used in the process of experiment and teaching. At present, there are many kinds of instruments and methods used to verify the law of conservation of angular momentum. However, most of the experimental results are not satisfactory due to the experimental errors caused by various factors, especially the non-negligible friction force and other factors. This method is to measure the angular momentum before and after the heavy ball falls by using the air-cushion turntable. A bar-shaped light-blocking film with a width of about 5-8mm is fixed on the turntable, and two short-distance photoelectric gates are set. The law of conservation of angular momentum is verified by the method of measuring the linear velocity with a bar-shaped light barrier. Using the newly invented linear velocity method overcomes these unfavorable factors and reduces the experimental error from nearly 30% to 1.7%.

Description

technical field [0001] The method of verifying the law of conservation of angular momentum with linear velocity is an invention of an experimental method, that is, the method of measuring linear velocity with a bar-shaped light barrier, which is mainly used in experiments and teaching processes. Background technique [0002] According to the law of conservation of angular momentum, when the resultant external torque on a rigid body is zero, the value of its angular momentum Iω remains unchanged. I is the moment of inertia of the rigid body, and ω is the rotational angular velocity of the rigid body. [0003] At present, there are many instruments and methods used to verify the law of conservation of angular momentum. The commonly used angular momentum measuring instrument has experienced the development process from vertical turntable to platform turntable to air cushion turntable. The air-cushion turntable is the latest instrument that appeared in China after 2000. It adop...

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Problems solved by technology

[0007] However, in the test, the falling of the heavy ball caused the friction between the concave disc and the air-cushion turntable to increase suddenly, and the rotation speed of the concave disc decreased rapidly. Due to the experimental method, the systematic error of the air-cushion turntable and the limitations of the experimenter's operation, it was difficult to control The falling time of the heavy ball is in a critical state, and the experimental error is as high as about 30%, which leads to the failure of the experiment

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