CN206115810U - Centripetal force experimental apparatus - Google Patents

Abstract

For the quick and accurate expression formula of verifying centripetal force, the utility model provides a centripetal force experimental apparatus relates to a middle school physics mechanics teaching and laboratory glassware. The device is mainly by the base, the support, and the safety cover, the time -recorder, the protractor becomes with motor group. According to the utility model provides a design, the device's pendulum ball's motion becomes mechanical control by original manual control, and pendulum ball's horizontal movement track more is close standard circle, and the time measurement also truns into the time -recorder to by the manual work measurement to be measured from dynamic testing, and experimental error reduces greatly, just can accurately calculate the result fast through simple angle and meaurement of time, more is favorable to developing of experiment and teaching.

Description

A kind of centripetal force experimental provision

Technical field

This utility model is related to a kind of Middle School Physics mechanics teaching and experimental apparatus.

Background technology

The experiment of " verifying the expression formula of centripetal force roughly with conical pendu0 " is《Physics》Required 2（People teaches version）" centripetal force " one The content of section, is that bead one end that cord connects is fixed on iron stand, and the blank sheet of paper for being decorated with concentric circular is tiled on the table, The support of iron stand is adjusted, makes bead that the center of circle of concentric circular is located just at when vertically hanging static.Hand-motion bead is used, bead is allowed Do taper swinging momvement, i.e. bead under the drive of cord to move in a circle in the horizontal plane, the stopwatch when motion is stablized relatively Measurement bead motion n circles time t used, the cycle T that bead moves in a circle is obtained using the time and the number of turns of measurement, so as to calculate Go out the angular velocity omega of conical pendu0, substitute into the size that formula calculates centripetal force；Observe little straight down from the top of iron stand simultaneously The circular motion of ball overlaps with which concentric circular, this circle, the radius r justified with ruler measurement markers under labelling；Bead is measured again Apart from the length of hitch point, if accurate measurement will also measure the diameter d of bead, the radius of bead is counted pendulum length.According to by The principle that centripetal force is provided with joint efforts of gravity and rope pulling force, by making a concerted effort for Calculation and Analysis of Force pulling force and gravity.Using repetition Above-mentioned experimentation, compare with joint efforts with the size of centripetal force, finally draw experiment conclusion.

This experiment is all fine in terms of the property of may participate in of design, principle, method and student, but deposits in practical operation It is not enough several：1st, because being to use hand-motion bead in concrete operations, it is difficult to certain circular motion of bead on paper is made, Bead does in the horizontal plane elliptic motion mostly；2nd, when moving in a circle between paper there is a certain distance in bead, it is impossible to It is determined that move on which circumference actually, the radius r of measurement is very big with the radius error of bead actual motion；3rd, the fortune of conical pendu0 Dynamic time and the number of turns measure judgement by student with stopwatch and naked eyes.So the experimental result error that final student measures is larger, Teacher needs to make more explanation in teaching process, and student is not high to the credibility tested, and does not reach verification the verifying results.

The content of the invention

In order to quickly and accurately verify the expression formula of centripetal force, the above is overcome the shortcomings of, make the credible increasing of experiment By force, the motion that can guarantee that bead is close to real taper swinging momvement, reduction measurement error of the experimenter to the time, allows student again Property of participation is strong, easy to operate, and this utility model provides a kind of centripetal force experimental provision, is related to a kind of Middle School Physics mechanics teaching With experimental apparatus.The device mainly by base, support, protective cover, timer, protractor and motor unit are into whole as one Body is very easy to use.According to design provided by the utility model, the motion of the swing ball of the device is by original manual Control is changed into Mechanical course, and closer to standard round, measure of time also switchs to timing by manual measurement for the horizontal movement track of swing ball Device and photogate automatic measurement, experimental error is greatly reduced, just can be rapidly and accurately by the measurement of simple angle and time Calculate result.It is more beneficial for the development tested and impart knowledge to students.It is main that this utility model solves the scheme that its technical problem adopted Have it is following some.

1st, a T-shape bar is fixed in the rotating shaft of motor, when the motor is operated, swing ball can follow T-shape bar one Rise and rotate, so as to realize that the motor with adjustable speed replaces regulation manually, make the motion of swing ball more stable, the angular velocity measured It is more accurate.

2nd, an asymmetric T-shape bar is fixed in the rotating shaft of motor, swing ball and cycloid is made with motor movement When can automatically obtain a drift angle, keep the kinestate of conical pendu0.

3rd, one 90 degree of large-scale protractor is fixed in asymmetric T-shape bar short end, can be straight after swing ball motion stabilization Connect the drift angle for reading cycloid and initial position.

4th, the brake sack of a photogate is fixed at asymmetric T-shape bar length end, when swing ball motion stabilization, starts meter When device, brake sack is recorded by the number of times of photogate and total shading time by timer automatically.

5th, one fixing nut and two adjusting nuts are installed in the bottom of device, for adjusting and determine swing ball just Beginning position, with ensure below drift angle determine accuracy.

6th, two pieces of dismountable semicircle protective covers are installed additional on the both sides of support, to ensure that student participates in safety when testing Property.

The beneficial effects of the utility model are that the rotating speed of motor is adjustable, stable, than using handss specification, can guarantee that swing ball in water The circular motion that rotation in plane is near the mark；Shading number of times and total screening with the timer measuring brake sack with photogate The light time determine the angular velocity of swing ball motion than with the naked eye with the accurate many of stopwatch；When whole T-shape holder pivots it is steady When, directly the drift angle of cycloid and initial position can rapidly be read by protractor, experimental error is greatly reduced；Whole experiment With the experiment difference on teaching material less, simple to operation, student's property of participation is strong for principle and experimentation.

Description of the drawings

This utility model is further illustrated with reference to the accompanying drawings and examples, wherein：

Fig. 1 is experimental principle block diagram of the present utility model.

Fig. 2 is structural representation of the present utility model.

Specific embodiment

The utility model proposes a kind of centripetal force experimental provision, can relatively accurately measure the pivot angle θ and angle speed of bead Degree ω, as shown in figure 1, so as to draw experimental result rapidly.

Structural representation of the present utility model is as shown in Fig. 2 including adjusting nut（1）, base（2）, swing ball（3）, cycloid （4）, support（5）, protractor（6）, asymmetric T-shape bar（7）, crossbeam（8）, the small size motor with speed-regulating switch（9）, protective cover （10）, brake sack（11）, the timer with photogate（12）.In this embodiment, pendulum length L is measured with rule first (thick As long as slightly measuring cycloid length, if accurate measurement then will add swing ball radius) and cycloid hitch point to motor Shaft centerline apart from r₀, adjust the adjusting nut of bottom two, make cycloid under static state with the zero graduation line of protractor Alignment, to determine the initial position of cycloid；Then start slow actuating motor from low-grade, allow swing ball and whole T-shape to prop up Frame is rotated in the counterclockwise direction together, when ramping up to stability of rotation, the drift angle of cycloid and initial position can be observed almost Keep constant, record drift angle registration θ on now protractor.According to the synthesis knowledge of power, bias angle theta is substituted into formula

F₁=mgtanθ

Just can quickly calculate the F that makes a concerted effort suffered by swing ball₁。

After swing ball and cycloid stability of rotation, while timer and photogate are opened, during record swing ball motion stabilization Number of times and total shading time of the brake sack by photogate.According to the shading number of times and total shading time meter of timer record The cycle T of swing ball motion is calculated, using circular motion formula the angular velocity omega of swing ball is calculated, can using trigonometric function relational expression The circular motion radius for calculating swing ball are

r= r₀+L·sinθ

Swing ball moving radius r and angular velocity omega are substituted into centripetal force formula

F₂=mω²r

Just can quickly calculate the centripetal force F suffered by swing ball₂。

Because quality m of the swing ball in whole experiment process keeps constant, so the concrete numerical value that there is no need to measure m is come, The F that makes a concerted effort for calculating₁With centripetal force F₂All it is the expression formula containing m_。It is repeated several times by above-mentioned experimentation, each conjunction of comparison Power F₁With centripetal force F₂Size, just can smoothly draw experiment conclusion.

Claims (6)

1. a kind of centripetal force experimental provision, the device is mainly by base, support, protective cover, timer, protractor and motor unit Into, it is characterised in that a T-shape bar is fixed in the rotating shaft of motor, when the motor is operated, swing ball can follow T-shape bar Rotate together, so as to realize that the motor with adjustable speed replaces regulation manually, make the motion of swing ball more stable, the angle speed measured Degree is more accurate.

2. a kind of centripetal force experimental provision according to claim 1, it is characterised in that fix in the rotating shaft of motor Individual asymmetric T-shape bar, makes swing ball that a drift angle is automatically obtained when with motor movement, keeps the motion shape of conical pendu0 State.

3. a kind of centripetal force experimental provision according to claim 1, it is characterised in that solid in asymmetric T-shape bar short end Fixed one 90 degree large-scale protractor, can directly read the drift angle of cycloid and initial position after swing ball motion stabilization.

4. a kind of centripetal force experimental provision according to claim 1, it is characterised in that solid at asymmetric T-shape bar length end The brake sack of a fixed photogate, when swing ball motion stabilization, starts timer, and brake sack is recorded automatically by light by timer The number of times of electric switch and total shading time.

5. a kind of centripetal force experimental provision according to claim 1, it is characterised in that the bottom of device install one it is solid Determine nut and two adjusting nuts, for adjusting and determine the initial position of swing ball.

6. a kind of centripetal force experimental provision according to claim 1, it is characterised in that installing two pieces additional on the both sides of support can The semicircle protective cover of dismounting, to ensure that student participates in safety when testing.