CN2938073Y - Rotation liquid combined test instrument - Google Patents

Abstract

A rotating liquid comprehensive experimental instrument, which consists of a rotating mechanism, a speed control and adjustment module, a speed measuring and display module, a laser and measuring components. The rotating mechanism is placed in a box, and the disc on the upper end surface of the box is fixed on the motor bearing. It can rotate smoothly with the motor. There are speed control switch, forward and reverse toggle switch, speed digital display and laser power supply on the panel of the cabinet. Two support rods with scales are vertically fixed on the cabinet. The support rods are used for measuring And fix the measurement parts required for different experimental contents and make its position and direction adjustable. The utility model provides a rotating liquid comprehensive physics experiment device capable of measuring gravity acceleration, viscosity coefficient and optical system research.

Description

Rotary Liquid Comprehensive Experimental Instrument

technical field

The invention relates to a physical experiment device, in particular to a rotating liquid comprehensive experiment instrument capable of quantitatively measuring gravity acceleration and liquid viscosity coefficient.

Background technique

The acceleration of gravity is a very important physical quantity. In the teaching of university physics experiments, the following methods and instruments for measuring the acceleration of gravity are commonly used:

1, free fall method, it is that a kind of initial velocity is zero according to free fall, and acceleration is the uniformly accelerated rectilinear motion of g, namely $h=\frac{1}{2}\mathrm{<figure-callout\; id="2"\; label="g\; t"\; filenames="Y20062010466400081.png"\; state="\{\{state\}\}">g</figure-callout>}{t}^{}{}^2$ If the velocity of the object falling to a certain height is v ₀ , then the falling height of the object within t time at this height is $h=v_{0}t+\frac{1}{2}\mathrm{<figure-callout\; id="2"\; label="g\; t"\; filenames="Y20062010466400081.png"\; state="\{\{state\}\}">g</figure-callout>}{t}^{}{}^2,$ In the experiment, the height h _i (i=1, 2, 3, ...) corresponding to a series of nt (n=1, 2, 3, ...) is measured by the free fall instrument, and the above formula can be used according to the quadratic step-by-step The principle of difference method derives the gravitational acceleration g.

II. Air-cushion guide rail method, adjust the air-cushion guide rail to have an inclination angle, and the slider moves in a uniformly accelerated linear motion from top to bottom. Place a photoelectric gate at the upper and lower positions of the air rail to measure the speed of the slider respectively. Use the corresponding formula to find the acceleration due to gravity.

III. The simple pendulum method. When the pendulum angle is small, the air resistance is ignored. The swing of the simple pendulum in the vertical plane is a simple harmonic vibration, and the vibration period is $T=2\mathrm{\&pi;}\sqrt{L/g}$ In the formula, L is the pendulum length; g is the gravitational acceleration. After measuring T and L, g can be calculated by the following formula: g=4π ² L/T ² . See: Patent "Experimental Apparatus for Measuring Gravitational Acceleration Using a Pendulum"<ApplicationNo.> 02219720.

The viscosity coefficient is a physical quantity used to characterize the viscosity of the moving fluid. It is necessary to determine the viscosity coefficient in the selection of lubricating oil used in various machinery, hydraulic transmission and the study of the actual fluid motion law. The falling ball method is commonly used in college physics experiment teaching. When a small ball moves in a liquid, it is affected by three forces: gravity, buoyancy, and viscous force. If the liquid is infinitely extended and does not generate vortices during motion, then according to Stokes’ law, the viscous force on the ball is f=3πηdv where d is the diameter of the ball and v is the falling speed of the ball , η is the viscosity coefficient of the liquid. After a period of time, the ball falls at a constant speed, and the sum of the viscous force and the buoyant force is equal to the gravity of the ball. can be derived from the formula $\mathrm{\&eta;}=\frac{(\mathrm{\&rho;}-{\mathrm{\&rho;}}_0)\mathrm{<figure-callout\; id="2"\; label="g\; d"\; filenames="Y20062010466400081.png"\; state="\{\{state\}\}">g</figure-callout>}{d}^{}{}^2}{18v}$ (ρ and ρ ₀ are the densities of pellets and liquid, respectively) measured and calculated. The content of the experiment mainly measures the time required for the ball to fall a certain distance, calculates the falling speed of the ball, and substitutes it into the formula to find the coefficient of viscosity. See: Patent "Measuring Apparatus for Viscosity Coefficient by Falling Ball Method"<ApplicationNo.> 02215782.

The existing gravitational acceleration measuring instrument and viscosity coefficient measuring instrument are two independent experimental devices used in experimental teaching. The experimental content and measured physical quantities of the two are not many. As an independent experiment, students only need half of the experimental equipment. The experiment can be completed in less time, which will cause a waste of learning time and a decrease in efficiency. If these two instruments are not available in the teaching, the measurement of the acceleration of gravity and the coefficient of viscosity cannot be carried out.

Contents of the invention

The object of the present invention is to provide a rotating liquid comprehensive physics experiment device which integrates mechanics, electricity and optics and can measure acceleration of gravity, viscosity coefficient and study optical system.

The rotating liquid comprehensive experimental instrument provided by the present invention is composed of a rotating mechanism, a speed control and adjustment module, a speed measurement and display module, a laser and a measurement component. The rotating mechanism is placed in the box, and the disk on the upper end surface of the box is fixed on the motor bearing, which can rotate smoothly with the motor. The panel of the cabinet is equipped with a speed control switch, a forward and reverse toggle switch, a speed digital display, and a laser power supply. Two support rods with scales are vertically fixed on the box body. The support rod is used to measure and fix the measurement parts required for different experimental contents and make its position and direction adjustable. Measuring components include: horizontal screen with millimeter scale, horizontal marking line, horizontal protractor, vertical screen with millimeter scale, and tension cylinder. Cylindrical experimental containers are fixedly placed on the turntable. Its characteristics are: through the speed regulating switch, the experimental container filled with liquid on the turntable is rotated to achieve the rotation of the liquid, the liquid speed is displayed digitally, various related physical quantities are measured, and different physical experiments are carried out.

The present invention adopts the above-mentioned experimental principles and technical methods to form a comprehensive experimental device for rotating liquid. In the teaching of university physics experiments, this device can not only observe the phenomenon of centrifugal force qualitatively, but also use the upper concave surface of the rotating liquid as an optical system. To be studied, the acceleration of gravity and the viscosity coefficient of liquid can be measured quantitatively. This experiment combines the knowledge of fluid mechanics, geometric optics and physical optics, etc. The content is very rich, which can better train students' experimental ability and analysis ability, and improve the quality of physics experiment teaching.

Description of drawings:

Fig. 1 is the experiment apparatus figure of the present invention

Fig. 2 is the figure of experiment device of measuring gravitational acceleration g embodiment 2

Fig. 3 is the figure of experiment device of measuring gravitational acceleration g embodiment 3

Figure 4 is a diagram of the experimental device for verifying the relationship between the focal length of the paraboloid and the rotational speed

Figure 5 is a diagram of the experimental device for measuring the viscosity coefficient of liquid

1. Support rod with millimeter scale 2. Laser 3. Horizontal transparent screen with millimeter scale 4. Horizontal marking line 5. Spirit level 6. Cabinet 7. Laser power jack 8. Forward and reverse toggle switch 9. Speed control switch 10. Speed display window 11, turntable 12, cylindrical experimental container 13, horizontal protractor 14, millimeter scale vertical transparent screen 15, tension cylinder 16,

Zhang Si

Detailed ways

Example 1

The experimental device of the present invention is shown in Figure 1: it consists of a rotating mechanism, a speed control and adjustment module, a speed measurement and display module, a laser and a measurement component. The rotating mechanism is placed in the casing 6, and the turntable 11 on the upper end surface of the casing 6 is fixed on the motor bearing, which can follow the motor to rotate smoothly. The cabinet panel is provided with a speed regulating switch 10, a forward and reverse toggle switch 9, a speed digital display 10, and a laser power supply. A supporting rod 1 with a scale is vertically fixed on the instrument box 6, and the fixed position and direction of the supporting rod 1 are adjustable for different experimental content. The components include: a laser 2, a millimeter scale horizontal screen 3, and a horizontal marking line 4. Horizontal protractor 13, millimeter scale vertical screen 14, wire tension suspension cylinder 15, tension wire 16; cylindrical experimental container 12 is fixedly placed on the turntable 11 of box body 6; speed control switch 9 is connected with forward and reverse toggle switch 8 The speed control circuit displays the speed of the turntable through the display window 10.

Through the speed switch adjusted by the experimental device of the present invention, the experimental container placed on the turntable filled with liquid is rotated to achieve the rotation of the liquid, and the liquid speed is digitally displayed, so as to measure various physical quantities and different physical experiment contents.

Example 2

The acceleration of gravity g is measured by the height difference between the highest and lowest point of the rotating liquid surface, and the experimental steps are as follows:

Referring to accompanying drawing 3, the cylindrical experimental container 12 that fills liquid rotates with a certain speed through the speed regulating switch 9, and the liquid surface that fills in the inside forms a paraboloid, and the speed is displayed by 10 digits;

Change the rotational speed n (rotation/second) of the experimental container (ω=2πn), align the bottom and the highest point of the parabolic surface of the rotating liquid with the horizontal marking line 4, and read the highest and lowest liquid level on the support rod 1 with scale Calculate the height difference Δh, measure the diameter D of the experimental container with a vernier caliper, according to the formula $g=\frac{{\mathrm{\&pi;}}^2{\mathrm{D.}}^2{\mathrm{no}}^2}{7200\&Center\; Dot;\mathrm{\&Delta;h}}$ Computes the acceleration due to gravity g.

Example 3

Use the slope method to measure the acceleration of gravity g, see Figure 4. Place the millimeter-scale horizontal screen 3 above the cylindrical experimental container 12 filled with liquid, the laser beam of the laser 2 is incident parallel to the rotation axis, pass through the millimeter-scale horizontal screen 3, and align with the mark at the bottom of the container 12 x ₀ =R/, measure Go out the distance H of the transparent screen 3 to the bottom of the container 12, and the height h when the liquid level is still; the speed control switch 9 changes the cylindrical experimental container 12 rotating speed n (rev/min) $(\mathrm{\&omega;}=\frac{2\mathrm{\&pi;n}}{60}),$ Read the distance d between the incident light and the reflected light point BC on the millimeter scale horizontal screen 3, then $\mathrm{the\; tan}2\mathrm{\&theta;}=\frac{d}{h-h},$ Find the value of tanθ, according to the formula $g=\frac{2{\mathrm{\&pi;}}^2\mathrm{D.}}{3600\sqrt{2}\mathrm{the\; tan}\mathrm{\&theta;}},$ Find the acceleration due to gravity g.

Example 4

To verify the relationship between the focal length of the paraboloid and the rotational speed,

With reference to accompanying drawing 5, the vertical screen 14 of millimeter scale is put into the center of the experiment container that fills liquid through the rotating shaft, by the speed regulating switch 9, rotate with a certain speed, the liquid surface that fills in the inside forms a paraboloid, and the speed is displayed by digital 10;

The laser beam is incident on the rotating liquid surface parallel to the rotating axis, and then focused on the vertical screen. The incident position can be changed to observe the focusing situation. By changing the speed n (rev/min) $(\mathrm{\&omega;}=\frac{2\mathrm{\&pi;n}}{60}),$ Observe the focal position on the vertical screen after the laser beam is incident parallel to the axis of rotation, read the distance between the focal point and the bottom of the liquid concave surface with the scale on the horizontal marking line 4 and the vertical screen 14 and the scale on the support rod 1, which is the actual focal length; focal length of a paraboloid $f=\frac{\mathrm{<figure-callout\; id="2"\; label="g"\; filenames="Y20062010466400081.png"\; state="\{\{state\}\}">g</figure-callout>}}{2{\mathrm{\&omega;}}^2}$ The formula calculates the comparison between the focal length at each speed and the actual focal length. Obtained focal length versus rotational speed plot.

Example 5

To measure the viscosity coefficient of the liquid, with reference to accompanying drawing 5, pour a certain amount of liquid in the cylindrical experimental container 12, vertically immerse the cylinder 15 suspended by the tension wire in the liquid, the center of the cylinder is consistent with the axis of rotation, and the horizontal protractor 13 The center hole of the cylinder is aligned with the steel wire, so that the steel wire just passes through the small hole, and the surroundings cannot touch each other; there is a scale mark on the upper surface of the cylinder 15, adjust the position of the laser 2 so that the laser light passes through the protractor 13 vertically and then aligns with the column when the liquid is still. The scale marks on the surface record the corresponding angle of the laser on the horizontal protractor 13 at this time; then turn on the speed control switch 9, rotate at a low speed, and the rotating speed is displayed by a digital display 10; the cylindrical experimental container 12 rotates at a constant angular velocity ω ₀ , When the rotation speed is small, the fluid rotates regularly layer by layer. When the cylinder is stable, the angular velocity of the cylinder is zero. At this time, the position of the laser 2 is adjusted so that the laser light passes through the protractor 13 vertically and then aligns with the stationary cylinder surface. record the angle corresponding to the laser on the horizontal protractor 13; the difference between the two angles recorded before and after is the deflection angle θ of the cylinder; the cylinder deflection angle θ at different rotational speeds was measured in the experiment.

Use a spiral micrometer to measure the wire radius r, use a vernier caliper to measure the length L' of the wire, measure the distance Δz from the bottom of the cylinder to the bottom of the experimental container with a horizontal marking 4, measure the height L of the cylinder with a vernier caliper, and measure the radius R ₁ of the cylinder with a vernier caliper. Use a vernier caliper to measure the radius R of the experimental container, find out the shear modulus G of the metal wire,

According to the formula: $\mathrm{\&eta;}=\frac{G{r}^A}{2L^{\&prime;}{\mathrm{\&omega;}}_0}\mathrm{\&theta;}\left[\frac{2\mathrm{\&Delta;z}({R_1}^2-R^2)}{8\mathrm{L\&Delta;z}{R_1}^2{\mathrm{<figure-callout\; id="2"\; label="R"\; filenames="Y20062010466400081.png"\; state="\{\{state\}\}">R</figure-callout>}}^2+({R_1}^2-R^2)R^4}\right],$ Calculate the viscosity coefficient η of the liquid.

Claims (3)

1. A rotating liquid comprehensive experimental instrument is composed of a rotating mechanism, a speed control adjustment module, a speed measuring and display module, a laser and a measuring component. It is characterized in that the rotating mechanism is placed in the box body 6, and the box body (6) is vertical Fix the support rod (1) with scale, the parts required for different experimental contents whose fixed position and direction can be adjusted on the support rod (1), the parts include: laser (2), millimeter scale horizontal screen (3), horizontal Marking line (4), horizontal protractor (13), millimeter scale vertical screen (14), tensioned wire suspension cylinder (15), tensioned wire (16); the center of box body (6) has the turntable ( 11), the cylindrical experimental container (12) is fixedly placed on the turntable (11), and the turntable (11) is fixed on the bearing of the motor inside the box; the speed control switch (9) and the forward and reverse toggle switch (8) are connected to the speed control The circuit also displays the speed of the turntable through the display window (10). 2. The rotating liquid comprehensive experiment apparatus according to claim 1, characterized in that the laser (2) is fixed on the support rod (1), its position and direction can be adjusted, and the power is supplied through the laser power jack (7) on the panel. 3. The rotating liquid comprehensive experimental apparatus according to claim 1, characterized in that two support rods (1) with scales are vertically fixed on both sides of the cylindrical experimental container (12) on the apparatus box (6).

Images