Method for measuring Young's modulus of metal wire by lever weighting

Abstract

The invention provides a method for measuring the Young's modulus of a metal wire by lever weighting and relates to physical parameter measurement. In order to simplify Young's modulus measurement, the technical scheme is as follows: a supporting rod is fixed on a base; a platform is fixed at each of the middle part and the top of the supporting rod; a supporting column is arranged on the platform at the top; the top of the supporting column is a fulcrum of a lever and the lever ratio is 1:n; the upper end of the metal wire is fixed at the tail end of the left side of the lever; the lower end of the metal wire is fixed on the left side face of the platform located in the middle and the length of the metal wire is L; a metal thin rod and a scale are suspended at the tail end of the right side of the lever; a pointer is fixed on the platform at the top and the tail end of the pointer is in a horizontal state; a tray is fixed at the lower end of the metal thin rod and the reading of the scale is x1; after m kilograms of heavy objects are put on the tray, the reading is x2 and the elongation amount deltaL of the metal wire under the action of the heavy objects is equal to |x1-x2| / n; the diameter d and the length L of the metal wire are measured and the Young's modulus Y is equal to 4m*g*n<2>*L / (pi*d<2>*|x2-x1|), wherein g is gravity acceleration and pi is the ratio of the circumference of a circle to the diameter. The method has the beneficial effects that the cost is saved and the adjustment is convenient.

Description

technical field [0001] The invention relates to the field of measurement of physical parameters, especially the measurement of Young's modulus of materials. Background technique [0002] The measurement of Young's modulus of metal wire is a common experiment in university physics experiments. It mainly uses the principle of optical lever amplification to measure the elongation of steel wire, so as to calculate the Young's modulus of steel wire. The parameters that must be measured are: the length of the wire, the diameter of the wire, the elongation of the wire, the mass of the added weight (use weights, the mass of 1 weight is 1 kg, generally use 8-9 Weights), the shortcomings of which are: [0003] The length measurement of the metal wire is inaccurate: because the upper end and the lower end of the metal wire are clamped by the clamp, the upper end clamp is fixed on the support plate of a support frame, and the lower end clamp is located in the center hole of the support...

AI Technical Summary

Problems solved by technology

[0003] The length measurement of the metal wire is inaccurate: because the upper and lower ends of the metal wire are clamped by the clamp, the upper clamp is fixed on the support plate of a support frame, and the lower clamp is located in the center hole of the support plate in the middle of the support frame. The effective length (the distance between the fixed point of the upper clamp and the fixed point of the lower clamp) of the root metal wire (generally steel wire) is different. The wire is approximately at a right angle, and if it is close to the metal wire, the tape measure will bend and cannot be close to the fixed point between the metal wire and the fixture, resulting in a large error in measurement

[0004] Measuring the elongation of the metal wire with a polished rod is more complicated: a vertical ruler is fixed next to the telescope, the upper surface of the lower end fixture of the steel wire fixes the rear feet of the polished rod, and the fulcrum (two front legs) of the polished rod is located in the middle of the support frame. On the support plate, there is a rotatable plane mirror above the two front feet of the light lever. The scale of the scale is reflected to the plane mirror of the light lever, reflected from the plane mirror to the telescope, and from the horizontal reference line of the telescope reticle (called the reading reference line) ) to read the scale of the scale, with the increase or decrease of the weight, the scale of the telescope's field of view is located on the reading reference line, and the relationship between the elongation of the steel wire and the weight of the weight is measured

It is necessary to adjust the verticality of the plane mirror, observe the ruler above the telescope, and find the ruler in the field of view of the telescope; there is an error in measuring the distance from the mirror surface of the polished rod to the rear foot, because the mirror is generally located in the middle of the frame, so it is generally simplified to measure the front and rear feet of the polished rod The distance between the two front feet is not necessarily within the mirror surface in mathematics; the distance between the mirror surface and the ruler needs to be measured at the same height, and the vertical distance cannot be tilted. These are difficult to be accurate experimentally.

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