CN2049807U

CN2049807U - Demonstrator for teaching free falling body

Info

Publication number: CN2049807U
Application number: CN 89212629
Authority: CN
Inventors: 甘小春
Original assignee: Individual
Current assignee: Individual
Priority date: 1989-06-27
Filing date: 1989-06-27
Publication date: 1989-12-20

Abstract

The utility model relates to a demonstrator for teaching a free falling body, which is designed according to the principle of electromagnetic induction. The demonstrator for teaching a free falling body mainly comprises a panel which is labeled with an orthogonal coordinate, a magnetic falling body and a falling through tube which is wound with a plurality of groups of coils; when a magnet falls through the falling through tube, a plurality of groups of luminous tubes which are positioned in the coordinate and are correspondingto the coils are lightened one by one; therefore, the required time, the instant velocity and the velocity diagram line of the falling body which reaches a certain predetermined point are displayed out, and the law of the motion of the free falling body is reflected out in a visible mode. The demonstrator for teaching a free falling body has the advantages of simple structure and easy fabrication; the demonstrator for teaching a free falling body can be demonstrated by one teacher. The demonstrator for teaching a free falling body is a teaching instrument with strong practicability.

Description

Demonstrator for teaching free falling body

The utility model relates to a kind of freely falling body demonstrator, belongs to instruments used for education.

In the existing physics lesson teaching, the teaching of relevant freely falling body chapters and sections is normally finished by books, and this method can not reflect the rule of the movement of falling object intuitively, is unfavorable for learning the profound understanding to this chapters and sections content.And the instrument of original this respect all can not be demonstrated falling bodies instantaneous velocity and speed figure line.

The purpose of this utility model provides a kind of freely falling body demonstrator, it can be by teacher's one man operation on the classroom, the time of demonstration freely falling body arrival preset and instantaneous velocity, speed figure line, thus help the student to be familiar with the rule of the movement of falling object more intuitively, sharpen understanding.

The utility model is to show the falling bodies instantaneous velocity according to electromagnetic induction principle.In formula ε=BLVsin α, if B.L.sin α is certain, then electromotive force ε will only be proportional to falling bodies speed V.We know that in the movement of falling object, the object falling speed is a variable (V=gt), this variable is incorporated in the above-mentioned formula, just can obtain being proportional to the ε of V, then ε be carried out analog to digital conversion, just can obtain the digital quantity of any preset instantaneous velocity in the object dropping process.Therefore, the utility model adopts magnet to do falling bodies, loads onto some groups of coils again on the route of magnet landing, and the coil that is in differing heights (being friction speed V), the identical number of turn will be induced into different electromotive force ε, so just finish the first step of analog-converted.

The utility model is described in further detail below in conjunction with accompanying drawing.

Fig. 1 is an example structure synoptic diagram of the present utility model;

Fig. 2 is the dispalying systems circuit theory (only draw the left side first group, all the other several groups of principles are identical) among Fig. 1;

Fig. 3 is a time control circuit schematic diagram of the present utility model;

Fig. 4 is a V-ε change-over circuit schematic diagram of the present utility model.

Among the figure, 1-falling bodies release, 2-falling bodies (magnet), 3-tongue tube (four), 4-coil, 5-whereabouts siphunculus, 6-timing contact, 7-carp folder, 8-light emitting diode, 9-electronic timepiece, the light-operated transmit-receive tube of 10-, 11-rest button, 12-power switch, 13-panel.

With reference to Fig. 1, being marked with the time (second) at panel (13) is that horizontal ordinate, falling bodies speed (meter per second) are the rectangular coordinate system of ordinate, be provided with several groups of light emitting diodes (8) corresponding to regular hour, speed in the coordinate, the number of each group luminotron increases progressively successively.Siphunculus (5) is parallel with ordinate, and panel border is fixed in its lower end, the upper end be one by microvesicle W and photoelectric tube BG ₂The light-operated transmit-receive tube of forming (10), falling bodies (2) just enter toward falling from this end.The available hand of falling bodies (2) discharges, also can adopt the falling bodies release (1) of Fig. 1, it has one to be fixed on the framework but the elongate bars that can twitch back and forth, be used for hanging up falling bodies (2), one fixed block is arranged on the stock, like this, when drawing back stock, the falling bodies (2) that are hung on its outer end just fall along whereabouts siphunculus (5) through light-operated transmit-receive tube (10) naturally, become freely falling body.Being tied with four groups (or more than four groups) coil (4) that the number of turn is identical on the siphunculus (5) (is the L among Fig. 4 ₁-L ₄), they are respectively 49,196,441,784 millimeters from the distance of initiating terminal.According to formula h=1/2 gt ²And V=gt calculates, and time and instantaneous velocity that falling bodies arrive them should be respectively 0.1,0.2,0.3,0.4 and 1,2,3,4 meter per seconds, the foundation of the coordinate displayed map in Here it is the construction drawing 1.For ease of student's direct feel to falling bodies drop difference in the identical time interval, marked distance between initiating terminal and each coil position with O, A, B, C, D, they are respectively that OA is 49 millimeters, the AB147 millimeter, the BC245 millimeter, the CD343 millimeter.(be the K among Fig. 4 near on the panel of coil (4) four tongue tubes (3) being housed ₁, K ₂, K ₃, K ₄), control four groups of light emitting diodes respectively.

With reference to Fig. 4, as the Ic of the input utmost point ₂Be connected into the totalizer of anti-phase input.When magnet (2) falls to also passing through successively L from siphunculus (5) upper end ₁, L ₂, L ₃, L ₄The time they will generate electromotive force (about fixed magnet N is extremely downward, and the electromotive force of inducting when making the N utmost point enter coil is a negative), they successively add to Ic by input resistance separately ₂Inverting input (6 pin), Ic at this moment ₂Only the negative input voltage is worked, output terminal will be exported a positive phase voltage (7 pin), and this voltage passes through C ₁R ₃Add to Ic ₃Inverting input (9 pin), Ic ₃Be connected into and exchange the form of amplifying, its 8th pin is exported a negative voltage, through C ₃R ₈Add to Ic ₄End of oppisite phase (13) pin amplify because the just negative voltage of input, so the utmost point need not biasing, BG ₁As the usefulness of expansion output current, W ₁Be used to adjust the enlargement factor of circuit.For guaranteeing the linearity of amplifying circuit, each extremely all adds degree of depth negative feedback.Four tongue tube (K ₁, K ₂, K ₃, K ₄) control four groups of light emitting diodes (8) respectively, when magnet (2) generated electromotive force in coil before, magnet (2) was its adhesive, and magnet discharges after by coil.

As tongue tube K ₁BG during by adhesive ₁The F point of e utmost point output voltage in Fig. 2 (with F point among Fig. 4 with), Ro adds to CR ₁The control utmost point, CR when this voltage reaches certain value (as 0.6 volt) ₁Conducting, luminotron LED ₁Light, when this voltage rises certain value (as 0.6 volt) again, D ₁, CR ₂Conducting, LED ₂Light, the rest may be inferred by analogy for it.

Between analog quantity and digital quantity, how quantitatively to change and to select arbitrarily.Present embodiment is selected ought light interval scale instantaneous velocity 1 meter per second by 5 luminotrons, when 10 luminotrons are lighted interval scale instantaneous velocity 2 meter per seconds.Below analogize.

Have four groups with the corresponding luminotron of coil (4) number (8), all vertically be arranged in the rectangular coordinate of panel, every group of contained luminotron number depends on the needs, instantaneous velocity when luminotron in the top of lighting corresponding to the longitudinal axis represents that falling bodies arrive this coil position represents that corresponding to transverse axis falling bodies arrive the time of this coil position.

In order to show that clearly falling bodies arrive certain any time, on panel, adorn a stopwatch (9) (for existing structure), it is subjected to the control of circuit shown in Figure 3.Referring to Fig. 3, by BG ₂Form light-operated transmit-receive tube (10) with W, be loaded on the reference position of siphunculus (5) top falling bodies.When magnet (2) falls to obstructing the light, a positive pulse is arranged through C ₅, D ₁, R ₁₀Add to Ic ₁In-phase input end (3 pin), export a positive pulse through R by 1 pin ₁₃Make D ₄Send infrared ray, D ₅Back resistance descends rapidly after receiving infrared ray, because D ₅Be oppositely to be serially connected between the positive pole and Time Triggered point of stopwatch (9), at this moment stopwatch (9) is triggered and picks up counting.When magnet (2) N polar plane drops to coil L ₁During the position, will be descended rapidly by the 1. some current potential among preceding described Fig. 2, and produce a negative pulse, this negative pulse is to draw by a certain timing contact (6) of panel bottom among Fig. 1, and the lead by carp folder (7) is connected to the E point among Fig. 3 again, through C ₆, D ₃, R ₁₂Add to Ic ₁Inverting input 2 pin, make it to produce positive pulse output, the electronic watch timing is stopped.When carp being pressed from both sides (7) reconfiguration, just can measure the time of the corresponding coil position of magnet (2) arrival respectively to the timing contact of other several groups of light emitting diodes.

In sum, when magnet (2) passes through four coils from top to down, four groups of light emitting diodes are topmost all lighted two successively except that every group from left to right, so just what time in coordinate, demonstrate a speed figure line of forming by o, a, b, c, d corresponding to O, A, B, C, D, students can check according to this instrument mark and the measured next every formula of data substitution, and be familiar with the movement of falling object intuitively, thereby deepen the understanding of students to movement of falling object rule.

This device is novel, and is simple in structure, makes easily, in light weight, can show that falling bodies arrive instantaneous velocity and the speed figure line of predetermined point by teacher's one man operation demonstration, reflects more intuitively movement of falling object rule, is a kind of practical instruments used for education. This device also can be used for asking acceleration of gravity 9.

Embodiment: panel (13) is used timber, siphunculus (5) ebonite tube (or lucite). 4 Ic are 1/4 LN324 K₁、K ₂、K ₃、K ₄Be JAG-2, LED₁－LDE ₇Be 2EF1A, D₄、D ₅Be respectively the Emission and receiving of infrared diode, the circuit among Fig. 2-Fig. 4 concentrates on the circuit board, is installed in the reverse side of panel (13).

Claims

1, a kind of freely falling body demonstrator, comprise device part and circuit part, it is characterized in that device partly comprises a panel (13) that indicates rectangular coordinate, magnetic falling bodies (2) and be fixed in panel and can pass through the whereabouts siphunculus (5) of falling bodies (2), be wound with the identical coil (4) of at least four group numbers of turn on this siphunculus, on the close panel (13) of coil, several and the corresponding tongue tube of coil (4) (3) are housed, in above-mentioned rectangular coordinate, several groups of luminotrons (8) are housed corresponding to coil (4) number, every tongue tube (3) communicates with one group of luminotron (8) respectively, and to be subjected to coil (4) thereby the electromotive force of being inducted orders about closed or disconnect and control every group of luminotron (8) for every tongue tube (3); Whereabouts siphunculus (5) top is microvesicle W and photoelectric tube BG ₂The light-operated transmit-receive tube of forming (10), it controls the stopwatch (9) that is loaded on the panel according to falling bodies (2) through the differing heights of siphunculus (5).

2, freely falling body demonstrator according to claim 1 is characterized in that panel (13) top is provided with a falling bodies release (1), and it mainly is the stock that can twitch back and forth and is positioned at fixed block on this stock.

3, freely falling body demonstrator according to claim 1 is characterized in that panel (13) is provided with timing contact (6) corresponding to every group of luminotron (8).