CN102938226A - Comprehensive demonstration instrument for demonstrating angular momentum conservation and rotational inertia and demonstrating method thereof - Google Patents

Abstract

The invention relates to a comprehensive demonstration instrument for demonstrating the conservation of angular momentum and moment of inertia, which is characterized in that it includes a single-chip microcomputer, a rope-drawing motor, a frequency conversion drive motor, and the single-chip microcomputer is used as the control center of the comprehensive demonstration instrument; it also includes a support shaft and a support shaft There is a rotating arm that rotates on the top, and a heavy ball is set on each side of the rotating arm. The heavy ball is connected with the pull rope, and driven by the pull rope motor, the two heavy balls are pulled inward/outward synchronously along the rotating arm. Movement; the support shaft is connected to the center of the outer turntable below, and there is a card slot under the outer turntable, which is in the shape of a gear; the inner turntable is arranged in the card slot, and the inner turntable is fixedly connected to the clamping plate through a torsion spring, and the clamping plate and the card Corresponding to the groove; the variable frequency drive motor is turned on, the inner turntable is driven by the variable frequency drive motor to rotate, the torsion spring is deformed, the clamp plate is engaged with the slot, and the outer transmission plate is driven to rotate, and the outer transmission plate drives the support shaft to rotate; the frequency conversion drive motor is stopped, and the speed of the inner turntable is lower than that of the outer transmission The rotation speed of the disc is reset by the torsion spring, and the clamping plate breaks away from the clamping slot.

Description

Comprehensive Demonstration Apparatus and Demonstration Method for Demonstrating Conservation of Angular Momentum and Moment of Inertia

technical field

The invention relates to a comprehensive demonstration instrument for demonstrating conservation of angular momentum and moment of inertia and a demonstration method thereof, belonging to the technical field of scientific and educational equipment.

Background technique

With the upgrading and development of science and education products and the improvement of social needs, universities and some scientific research manufacturers are also turning their attention to the market of science and education products. The law of conservation of angular momentum is one of the most common laws in nature. The theories of conservation of angular momentum and rotation are widely used in real life, such as simulating the use of gravity in the aerospace industry; the law of rotation and the law of conservation of angular momentum are important in mechanics. For the two knowledge points, however, the teaching devices for the demonstration of the principles of the existing conservation of angular momentum and the theorem of rotational inertia are all separated.

Generally, the device for verifying the conservation of angular momentum is a swivel chair that can rotate freely around the vertical axis. The display method is as follows: the demonstrator sits on the swivel chair, holds dumbbells in his hand, and stretches his arms flat. Make the swivel chair rotate, and then retract the arms, you can see that the rotation speed of the person and the stool increases significantly. The arms were stretched out again, and the speed slowed down. This is because the angular momentum of an object rotating around a fixed axis of rotation is equal to the product of its moment of inertia and angular velocity, and when the external torque is equal to zero, the angular momentum is conserved. When a person retracts the arms, the moment of inertia decreases, so the angular velocity increases.

Generally, the device for verifying the moment of inertia is to demonstrate the moment of inertia of two rigid objects separately, and compare them, thereby verifying the principle of the moment of inertia, and the result can only be observed with the naked eye.

To sum up, the existing rotational inertia demonstration device and angular momentum conservation demonstration device are two independent devices, which need to be demonstrated respectively, and there is no digital display, which can only be observed with naked eyes, and the demonstration effect is not good.

Contents of the invention

The technical problem to be solved by the present invention is: the existing rotational inertia demonstration device and the angular momentum conservation demonstration device are two independent devices, which need to be demonstrated separately, and the demonstration effect is not good. In order to study and display its physical principles better, the present invention combines the two skillfully and uses computer control technology to develop a new type of comprehensive demonstration instrument for conservation of angular momentum and moment of inertia. Demonstrate the principles of the conservation of angular momentum and the theorem of rotational inertia through the same instrument, and realize the visualization of the dynamic process.

The present invention takes the following technical solutions:

A comprehensive demonstration instrument for demonstrating conservation of angular momentum and moment of inertia, comprising a single-chip microcomputer, a rope-drawing motor, and a variable frequency drive motor, and the single chip microcomputer, as the control center of the comprehensive demonstration instrument, can obtain the speed of the variable frequency drive motor; it also includes Supporting shaft 2, said supporting shaft 2 is provided with a rotating arm 4 which rotates therewith, and a heavy ball 1 is respectively sleeved on both sides of said rotating arm 4, said heavy ball 1 is connected with a stay cord 3, and said stay cord 3 is arranged along the rotating arm 4 and is driven by the rope-drawing motor to pull two heavy balls to move inward/outward synchronously along the rotating arm 4; the support shaft 2 is connected to the center of the outer turntable 7 below, There is a draw-in groove 701 below the outer turntable 7, and the draw-in groove 701 is in the shape of a gear; the inner turntable 8 is arranged in the draw-in groove 701, and the inner turntable 8 is fixedly connected with the clamp plate 801 by a torsion spring 802, so that The clamping plate 801 corresponds to the clamping slot 701; the variable frequency drive motor is turned on, the inner turntable 8 is driven to rotate by the variable frequency drive motor, the torsion spring 802 is deformed, the clamping plate 801 is engaged with the clamping slot 701, and the outer transmission disc 7 is driven to rotate , the outer transmission disk 7 drives the support shaft 2 to rotate; the variable frequency drive motor stops, the rotation speed of the inner rotation disk 8 is lower than the rotation speed of the outer transmission disk 7, the torsion spring 802 resets, and the clamping plate 801 breaks away from the clamping groove 802.

It also includes a display screen 5, which is connected to the single-chip microcomputer and can display the rotational speed of the variable frequency drive motor.

It also includes a button 6, which is connected with the single-chip microcomputer.

A method for demonstrating the conservation of angular momentum using the above-mentioned comprehensive demonstrator, comprising the following steps:

1) Small balls are located at both ends of the rotating arm 4;

2) Start the variable frequency drive motor, the support shaft 2 drives the rotation, the rotating arm 4 rotates, and the heavy ball 1 rotates synchronously;

3) After reaching the set speed, the variable frequency drive motor stops, and the clamping plate 801 is separated from the clamping slot 701;

4) The pull rope motor drives the pull rope 3 to pull inward, the two heavy balls 1 slide inward along the rotating arm 4 synchronously, and the rotating arm speeds up;

5) The pull rope motor pulls the pull rope 3 to the outside, and the two heavy balls 1 slide outward along the rotating arm 4 synchronously, and the rotation speed of the rotating arm slows down.

A method for performing a moment of inertia demonstration using the above-mentioned comprehensive demonstration instrument, is characterized in that, comprising the following steps:

1) Small balls are located at both ends of the rotating arm 4;

2) Start the variable frequency drive motor, the support shaft 2 drives the rotation, the rotating arm 4 rotates, and the heavy ball 1 rotates synchronously;

3) Record the rotational speed displayed on the display screen 5;

4) The variable frequency drive motor stops, the clamping plate 801 is separated from the clamping slot 701, and the rotating arm 4 rotates inertially;

5) Record the time required for the rotating arm 4 to stop;

6) Start the pull rope motor, the pull rope pulls the heavy ball 4 to move a certain distance to the middle and then stops, repeat the above steps 1) and 2);

7) until the rotation speed is the same as that in step 3);

8) Repeat steps 4), 5).

The present invention is characterized in that the demonstration of the principle of conservation of angular momentum and the theorem of moment of inertia is combined in the same experimental device, and a single-chip microcomputer is used as a control system to control the actual operation through buttons. At the same time, the structure of the chuck and the clamping plate is cleverly used, and the structure is simple. Using the torsion spring, the clamping plate can be separated from the clamping groove in the vertical direction without detaching from the clamping groove, and the drive to the support shaft 2 is conveniently realized. and stop driving.

The present invention aims at the present situation that the existing demonstration devices for the principle of the conservation of angular momentum and the theorem of moment of inertia are demonstrated separately, and the two are skillfully combined. Through the control of a single-chip microcomputer, the two principles can be comprehensively demonstrated, and the two principles can be more clearly demonstrated. See the dynamic change process of the whole principle demonstration, and record the change data at any time.

The beneficial effects of the present invention are:

(1) Reasonable structure and low cost.

(2) Easy to use and long cycle.

(3) High security and scientific.

(4) High degree of visualization and humanized design.

(5) It has commercial value and creates greater economic benefits.

Description of drawings

Fig. 1 is a schematic diagram of the appearance of the comprehensive demonstration instrument for the conservation of angular momentum and moment of inertia of the present invention.

Fig. 2 is a schematic front view of the external transmission disc.

Fig. 3 is a schematic bottom view of the outer turntable.

Figure 4 is a schematic bottom view of the inner turntable.

Fig. 5 is a schematic bottom view of the outer transmission disc meshing with the inner rotary disc.

Fig. 6 is a schematic bottom view of the outer disc separated from the inner disc.

Fig. 7 is a three-dimensional schematic view of the inner turntable and the clamping plate connected by torsion springs.

Among them, 1. Heavy ball, 2. Support shaft, 3. Pull rope, 4. Rotating arm, 5. Display screen, 6. Button, 7. Outer transmission disc, 8. Inner turntable, 701, card slot, 801 card board, 802. torsion spring.

Detailed ways

The present invention will be further described below in conjunction with specific examples.

As shown in Figure 1-7, a comprehensive demonstration instrument for demonstrating the conservation of angular momentum and moment of inertia includes a single-chip microcomputer, a rope motor, and a variable frequency drive motor. The single-chip microcomputer is used as the control center of the comprehensive demonstration instrument to obtain the variable frequency drive. The rotating speed of motor; also comprise supporting shaft 2, be provided with the rotating arm 4 that rotates thereupon on supporting shaft 2, respectively set a heavy ball 1 on both sides of described rotating arm 4, heavy ball 1 is connected with stay cord 3, stay cord 3 is arranged along the rotating arm 4, and is driven by the rope motor to pull two heavy balls to move inward/outward synchronously along the rotating arm 4; the support shaft 2 is connected to the center of the outer turntable 7 below, and the outer There is a card slot 701 below the turntable 7, and the card slot 701 is in the shape of a gear; the card slot 701 is provided with an inner turntable 8, and the inner turntable 8 is fixedly connected to the card plate 801 by a torsion spring 802, and the card plate 801 corresponds to the card slot 701; frequency conversion The driving motor is turned on, the inner turntable 8 is driven by the frequency conversion drive motor to rotate, the torsion spring 802 is deformed, the clamp plate 801 is engaged with the slot 701, and the outer transmission plate 7 is driven to rotate, and the outer transmission plate 7 drives the support shaft 2 to rotate; the frequency conversion drive motor stops, and the inner turntable 8. When the rotating speed is lower than the rotating speed of the external disc 7, the torsion spring 802 is reset, and the clamping plate 801 is separated from the clamping groove 802. It also includes a display screen 5, which is connected with the single-chip microcomputer and can display the speed of the variable frequency drive motor. It also includes a button 6, which is connected with the single-chip microcomputer to control the operation of the integrated demonstration instrument.

As shown in Figure 1, connect the power cord, turn on the power switch, and the display will display "Comprehensive Demonstration Instrument for Conservation of Angular Momentum and Moment of Inertia". "Two Ball Position Adjustment". In the "angular momentum experiment" mode, press the button in the middle, and the support shaft 2 rotates at this time, record the rotation speed of the support shaft 2 at this time, press the button on the right, and pull the heavy ball 4 close to the Support the position of the center of the shaft 2. At this time, the speed of the rotating arm 4 is obviously accelerated. After about 1 second, the variable frequency drive motor starts to maintain the speed of the rotating shaft 2 at about 256rpm. Press the button on the right again, and the two balls are released to the rotating arm. At both ends of 4, the speed of the rotating arm 4 obviously slows down now, and after about 1 second, the variable frequency drive motor is started, so that the rotating speed of the rotating arm 4 is maintained at about 97rpm, and so on.

Before switching to another mode, press the button in the middle to stop the variable frequency drive motor, then press the button on the left to switch modes, enter the "moment of inertia experiment" mode, press the button in the middle, at this time the double ball 1 Pulled close to the center of the rotating arm 4, the variable frequency drive motor rotates. After the speed reaches 210rpm, record the speed, and then press the button on the right. At this time, the variable frequency drive motor stops, the clamping plate 801 is separated from the clamping groove 701, and the supporting shaft 2 Continue to rotate under the action of inertia, and finally stop due to frictional resistance, the single-chip microcomputer records and stores the time elapsed from the inertial rotation of the support shaft until it stops; about 2 seconds later, the double balls are released to both ends of the rotating arm 4, and the variable frequency drive motor is started. Drive the support shaft 2 to rotate until it reaches the same speed as when the two balls are close to the center of the rod, press the button on the right, the frequency conversion drive motor stops, the clamp plate 801 is separated from the slot 701, and the support shaft 2 continues to rotate under the action of inertia, due to friction The resistance stops at last, and now the display screen shows the time when the double ball 1 stops at the two ends of the rotating arm 4 and near the center of the rotating arm 4 after moving at the same speed. The stop time at the end is longer, which verifies the theorem of moment of inertia.

Press the button on the left to enter the "Ball Position Adjustment" mode. During the experiment, the rope motor may have a little error in the distance between pulling the heavy ball 1 and releasing the heavy ball 1, or the power is suddenly cut off during the experiment. The position of the double ball may affect the next experiment. If the rope motor is blocked, it will burn out the rope motor. At this time, it is necessary to adjust the position of the double ball in this mode. Before the demonstration of the two experiments, be sure to set the small Ball releases to rotating arm 4 two ends, in order to avoid pull rope too much, burn out pull rope motor.

Press the button on the right, at this time the pull rope motor reverses, release the pull rope 3, the heavy ball 1 moves to both ends of the rotating arm 4 under the action of centrifugal force, press the middle button, the pull rope motor rotates forward, and the heavy ball 1 approaches The center of the swivel arm 4 moves.

Claims (5)

1. comprehensive demonstration instrument of demonstrating the conservation of angular momentum and moment of inertia is characterized in that:

Comprise single-chip microcomputer, the stay cord motor, variable frequency drive motors, described single-chip microcomputer can obtain the rotating speed of described variable frequency drive motors as the control center of described comprehensive demonstration instrument;

Also comprise back shaft (2), described back shaft (2) is provided with each sheathed heavy ball (1) of the described pivot arm of pivot arm (4) (4) both sides of thereupon rotating, described heavy ball (1) be connected along stay cord (3), described stay cord (3) arranges along pivot arm (4), and by described stay cord driven by motor, it is synchronously inwardly/outwards mobile along described pivot arm (4) to spur two heavy ball;

Described back shaft (2) is connected with the center of the outer rotary table (7) of below, and described outer rotary table (7) below has draw-in groove (701), and described draw-in groove (701) is gear shape;

Be provided with inner rotary table (8) in the described draw-in groove (701), described inner rotary table (8) is upper to be fixedly connected with clamp (801) by torsion spring (802), and described clamp (801) is corresponding with described draw-in groove (701);

Described variable frequency drive motors is opened, described inner rotary table (8) is driven by variable frequency drive motors and rotates, torsion spring (802) distortion, clamp (801) and draw-in groove (701) engagement, drive unofficial biography dishes (7) and rotate, described unofficial biography dish (7) drives back shaft (2) and rotates;

Described variable frequency drive motors is shut down, and inner rotary table (8) rotating speed is less than the rotating speed of unofficial biography dish (7), and torsion spring (802) resets, and clamp (801) breaks away from described draw-in groove (802).

2. comprehensive demonstration instrument as claimed in claim 1, it is characterized in that: also comprise display screen (5), described display screen (5) is connected with described single-chip microcomputer, can show the rotating speed of described variable frequency drive motors.

3. comprehensive demonstration instrument as claimed in claim 1, it is characterized in that: also comprise button (6), described button (6) is connected with described single-chip microcomputer.

4. a right to use requires 2 described comprehensive demonstration instruments to carry out the demenstration method of the conservation of angular momentum, it is characterized in that, may further comprise the steps:

1) bead is located at pivot arm (4) two ends;

2) start variable frequency drive motors, back shaft (2) drives and rotates, and pivot arm (4) rotates, and heavy ball (1) is rotated synchronously;

3) reach set rotating speed after, variable frequency drive motors is shut down, clamp (801) separates with draw-in groove (701);

4) stay cord driven by motor stay cord (3) spurs to the inside, and two heavy ball (1) are inwardly slided along pivot arm (4) synchronously, the pivot arm faster rotational speed;

5) stay cord motor pulling stay cord (3) spurs laterally, and two heavy ball (1) are outwards slided along pivot arm (4) synchronously, and the pivot arm rotating speed slows down.

5. a right to use requires 2 described comprehensive demonstration instruments to carry out the method for moment of inertia demonstration, it is characterized in that, may further comprise the steps:

1) bead is located at pivot arm (4) two ends;

2) start variable frequency drive motors, back shaft (2) drives and rotates, and pivot arm (4) rotates, and heavy ball (1) is rotated synchronously;

3) the upper rotating speed that shows of record display screen (5);

4) variable frequency drive motors is shut down, and clamp (801) separates with draw-in groove (701), and pivot arm (4) inertia rotates;

5) record pivot arm (4) is until stop the required time;

6) start the stay cord motor, stop after stay cord pulling heavy ball (4) is moved a segment distance to the centre, repeat above-mentioned steps 1), 2);

7) until rotating speed is identical with rotating speed in the step 3);

8) repeating step 4), 5).

Images