Circular motion research device
Technical field
The invention belongs to kinetics research device field, especially studies the dynamics device involved by circular motion.
Background technology
One fine rule is fastened a weight and moved in a circle in perpendicular, and weight pulling force in minimum point is more than gravity,
And minimum point pulling force it is maximum-this is all easily to want to show this phenomenon with experiment by theoretical proof, prior art discloses
A kind of device for studying circular motion:Vertical panel, the base for supporting vertical panel, vertical plane to be used for positioned at vertical panel lower end
Plate is made up of iron plate, in addition to one made of permanent magnet, be shaped as the magnetic pole of column, magnetic pole one end is adsorbed in vertical plane
Plate, the magnetic pole other end bolt a fine rule, and the upper end of fine rule is bolted to magnetic pole, and the lower end of fine rule hangs a weight.The device
Application method:The first step, weight is risen into certain altitude, and:1, fine rule is in linear state;2, fine rule deviates vertical position
Put.Second step, weight is discharged, weight starts to be shaped as the motion of circular arc, i.e.,:A part for circular motion.Selection is suitable
Off-position, such effect can be reached:Weight is discharged in this position, magnetic pole can be forgotten about it just.Theory analysis is as follows:
The pulling force that weight is subject to is represented with T, the gravity that weight is subject to is represented with G, the quality of weight is represented with m, represents that weight passes through with v
The speed of minimum point, the radius of weight circular motion is represented with r, is derived byThen, minimum point is obtained
Speed v is bigger, conclusion bigger pulling force T.Aid in explaining with the experiment:Magnetic pole is forgotten about it, and illustrates that pulling force T force of gravity is big.Experiment
Operator recorded the video of the experiment, when playing video frame by frame, find:Magnetic pole is not fallen in weight in minimum point
Under, but after substantially have passed through minimum point, magnetic pole is just fallen.Experimental implementation person repeats to test multiple, and recorded video is simultaneously every time
Play frame by frame, find the phenomenon.This phenomenon and theory are not inconsistent.Do not found before this phenomenon by people:To broadcast at a slow speed
Put just it is observed that this phenomenon.Outwelled from weight by minimum point to magnetic pole, about last 0.2 second.The time of 0.2 second,
About the device hangs 1/the 8 of weight period of single pendulum, and in this 0.2 second, the distance that weight passes through is about the three of amplitude
/ bis-, the angle of fine rule and vertical direction is about 40 degree.So not going out the phenomenon generally from the time, broadcast at a slow speed
When putting, it can deviate from weight and the phenomenon is observed in the distance of equilbrium position.
For strict, the experiment and theory are not inconsistent, and the experimental provision should not be used in the dynamic (dynamical) teaching of circular motion.Change
Sentence is talked about:A new device is researched and developed, minimum point pulling force can be demonstrated and be more than the experiment of gravity, and overcome drawbacks described above.
Since research and develop the problem of new device is it is necessary to know existing apparatus go out where.There are two kinds of sayings:1, fine rule
Deformation needs the time, and this time is about 0.2s, waits fine rule to complete deformation, and magnetic pole is just drawn by bigger pulling force
.2, magnetic pole just has begun to topple in weight by minimum point, and still, the length of magnetic pole falls short of, after 0.2 second,
It will become apparent from carrying out magnetic pole outwelling.Both sayings sound it is all reasonable, if judging which kind of saying is correct with knowwhy,
This is extremely complex theoretical question.
On this phenomenon, there are other explanations, those explanations can directly be excluded by theory analysis, so, in this theory
Just do not described in bright book.
The present invention proposes a kind of device, and the device can be with:1, verifying above two saying, which kind of is correct.2, overcome existing dress
The weak point put, and reach the beneficial effect that experimental phenomena is consistent with theory.
The content of the invention
Technical scheme is used by the present invention overcomes prior art deficiency:
Circular motion research device, including vertical panel, the base for supporting vertical panel is used for positioned at vertical panel lower end, is erected
Plate is faced directly to be fabricated from iron, in addition to one made of permanent magnet, be shaped as the magnetic pole of column, magnetic pole one end is adsorbed in vertical plane
Plate, the magnetic pole other end bolt a fine rule,
The upper end of fine rule is bolted to magnetic pole, and the lower end of fine rule hangs a spherical weight for being used for doing circular motion, and it is special
Sign is:
Vertical panel is fixedly connected with one and is used to make weight behind equilbrium position not by fine rule pulling force and constrain weight
The track of motion, the track are such:
Track is provided with the arc-shaped rail for being used for constraining weight motion, and arc-shaped rail is in the section shape of perpendicular
Circular arc, each section where arc-shaped rail perpendicular to vertical panel,
The radius of curvature of arc-shaped rail is less than the radius of trajectory,
The tangent line of arc-shaped rail bottom is horizontally oriented, and arc-shaped rail lowest positions are slightly below trajectory most
Low spot,
Distance of the arc-shaped rail upper end away from magnetic pole is less than the radius of trajectory,
Arc-shaped rail upper end be fixedly connected with one perpendicular to guide rail, for stopping that weight continues up the gear of swing
Piece,
Catch is fixedly connected with that two panels is relative, elastic card be arranged in parallel, for blocking weight, elastic card and
Arc-shaped rail does not contact, and plane where elastic card is perpendicular, and elastic card respectively has a phase in its inlet internal
To, projection for preventing weight from sliding, two raised horizontal ranges are less than the diameter of weight.
The arc length passed through along arc-shaped rail bottom to upper end is 1st to a thirtieth/10th of fine rule length.
Magnetic pole is shaped as cylinder.
Catch also sticks the cushion for buffering weight.
Cushion is made up of sponge.
Arc-shaped rail is flake.
The present invention is simple in construction, does related experiment with the present invention, experimental phenomena can be allowed to be consistent with theory analysis perfection.
Brief description of the drawings
Fig. 1 is the front view of prior art.
Fig. 2 is the side view of prior art.
Fig. 3 is the front view of the embodiment of the present invention one.
Fig. 4 is the partial elevation view of the embodiment of the present invention one.
Fig. 5 is the partial structural diagram of the embodiment of the present invention one.
Fig. 6 is the partial top view of the embodiment of the present invention one.
Fig. 7 is the partial top view of the embodiment of the present invention two.
In figure:1- vertical panels, 2- bases, 3- magnetic poles, 4- fine rules, 5- weights, 51- trajectories, 6- tracks, 61- circular arcs
Shape guide rail bottom, 62- arc-shaped rails, 63- arc-shaped rails upper end, 64- elastic cards, 641- is raised, 65- catch, 66-
Cushion.
Embodiment
Accompanying drawing 1,2 is the front view and side view of prior art respectively:Prior art includes vertical panel 1, positioned at vertical
The lower end of panel 1 is used to support the base 2 of vertical panel 1, and vertical panel 1 is fabricated from iron, in addition to one made of permanent magnet,
Be shaped as the magnetic pole 3 of column, the one end of magnetic pole 3 is adsorbed in vertical panel 1, and the other end of magnetic pole 3 bolts a fine rule 4, fine rule 4 it is upper
End is bolted to magnetic pole 3, and the lower end of fine rule 4 hangs a weight 5 for being used for doing circular motion.
Embodiment one
It is front view of the invention, circular motion research device, including vertical panel 1, positioned at vertical panel 1 referring to accompanying drawing 3
Lower end is used to support the base 2 of vertical panel 1, and vertical panel 1 is fabricated from iron, in addition to one made of permanent magnet, shape
For the magnetic pole 3 of column, the one end of magnetic pole 3 is adsorbed in vertical panel 1, and the other end of magnetic pole 3 bolts a fine rule 4, the upper end bolt of fine rule 4
Magnetic pole 3 is connected to, the lower end of fine rule 4 hangs a spherical weight 5 for being used for doing circular motion, it is characterized in that:
Vertical panel 1 is fixedly connected with one and is used to make weight 5 behind equilbrium position not by the pulling force of fine rule 4 and constrains weight
The track 6 that thing 5 moves.The track 6 is such:(it is the front view of the track 6, accompanying drawing 5 is the track 6 referring to accompanying drawing 4
Structural representation, accompanying drawing 6 is the top view of the track 6.)
Track 6 is provided with the arc-shaped rail 62 for being used for constraining the motion of weight 5, section of the arc-shaped rail 62 in perpendicular
Be shaped as circular arc, each section where arc-shaped rail 62 perpendicular to vertical panel 1,
The radius of curvature of arc-shaped rail 62 is less than the radius of trajectory 51,
The tangent line of arc-shaped rail bottom 61 is horizontally oriented, and the position of arc-shaped rail bottom 61 is slightly below trajectory
51 minimum point,
Distance of the arc-shaped rail upper end 63 away from magnetic pole 3 is less than the radius of trajectory 51,
Arc-shaped rail upper end 63 be fixedly connected with one perpendicular to guide rail, for stopping that weight 5 continues up swing
Catch 65, the place plane of catch 65 perpendicular to perpendicular,
Catch 65 is fixedly connected with that two panels is relative, elastic card 64 be arranged in parallel, for blocking weight 5, elasticity
Card 64 and arc-shaped rail 62 do not contact, and the place plane of elastic card 64 is perpendicular, and elastic card 64 is in its entrance
Respectively there is a projection 641 relative, for preventing weight 5 from sliding inside, and the horizontal range of two projections 641 is less than weight 5
Diameter.
Explain:Trajectory 51, trajectory 51 refer to weight 5 do circular movement (be referred to as simple harmonic motion, while
It is one section of arc of circular motion) when, the track of the bottom process of weight 5.Naturally, trajectory 51 is one section of circular arc.
Application method:Magnetic pole 3 is adsorbed in vertical panel 1, allows weight 5 to deviate equilbrium position, and ensure the shape of fine rule 4
Shape is straight line, and ensures that fine rule 4 parallel to vertical panel 1, then discharges weight 5, many experiments, finds this position:
When the position discharges weight 5, weight 5 can forget about it magnetic pole 3 in circular motion just.Mark the position.For the side of statement
Just, the position is designated as location A.
Weight 5 is pinched with hand, weight 5 is located at location A, is then started to this experiment shooting.
Weight 5 is discharged, after fine rule 4 is just through vertical direction, weight 5 has been put into arc-shaped rail 62, weight 5 one immediately
Denier and arc-shaped rail 62 are contacted, and the pulling force of fine rule 4 is reduced by, and weight 5 moves because inertia continues on arc-shaped rail 62, carefully
The pulling force of line 4 disappears, and loses the pulling force of fine rule 4 to weight 5 by equilbrium position from weight 5, the arc length passed through is very short, is undergone
Time it is also very short.When weight 5 reaches arc-shaped rail upper end 63, the region of the encirclement of elastic card 64 is entered, due to
Catch 65 is provided with, so weight 5 can not go out arc-shaped rail 62, because:Elastic card 64 respectively has one in its inlet internal
Individual relative, for preventing weight 5 from sliding projection 641, the horizontal range of two projections 641 are less than the diameter of weight 5, so,
Weight 5 will not also slide again to be come.
The above-mentioned video of slow play, it can be seen that:Fine rule 4 passes through vertical direction, enters arc-shaped rail 62, fine rule 4
Almost start simultaneously at bending ----that is pulling force disappearance.Magnetic pole 3 remains in that horizontal direction absorption in vertical panel 1, warp
The time of about 0.2 second is spent, substantially observes that magnetic pole 3 is toppled over from video.
Thus illustrate:1, do not see that weight 5 forgets about it magnetic pole 3 in minimum point to do the experiment with prior art, be not
Because the deformation of fine rule 4 needs the reason for corresponding time, but because toppling over for magnetic pole 3 is a process from slow to fast, incline
Starting stage, even if slow motion plays video, it is also difficult to find that magnetic pole 3 is substantially toppled over., can with device of the present invention
To prove:For weight 5 in minimum point, pulling force truly has maximum, and pulling force is more than the gravity of weight 5.
Embodiment two
Based on embodiment one, it can so optimize the present invention:Catch 65 also sticks the cushion for buffering weight 5
66.Cushion 66 can be made up of sponge.Cushion 66 can reduce the speed of weight 5.Referring to Fig. 7.
The present invention is explained further:
In order to allow weight 5 behind equilbrium position, as early as possible allow the pulling force of fine rule 4 disappear, can so limit:Along circular arc
The arc length that shape guide rail bottom 61 is passed through to upper end is 1st to a thirtieth/10th of the length of fine rule 4.So limit, so that it may
To exclude " because the deformation of fine rule 4 needs the time just to cause the delay of magnetic pole 3 to be toppled over ".
Can also so it optimize:
The shape of magnetic pole 3 can be cylinder.
Arc-shaped rail 62 is flake.
Each section, can not because arc-shaped rail 62 is curved surface perpendicular to vertical panel 1 where arc-shaped rail 62
Curved vertical is said in vertical plane, and says each section of curved surface perpendicular to perpendicular.
The radius of curvature of arc-shaped rail 62 is less than the radius of trajectory 51, and the words is to say, allows the moving radius of weight 5 to subtract
Small, it is 0 that can allow the pulling force of fine rule 4, thus it is possible to ensure the only under tension before fine rule 4 swings to vertical position of magnetic pole 3,
Fine rule 4 is swung to after vertical position, and weight 5 enters track 6 as early as possible, and weight 5 is supported by arc-shaped rail 62, fine rule 4
Pulling force disappears.Strictly speaking, fine rule 4 is after vertical position, and in by extremely short time, very short arc length, fine rule 4 is to magnetic
Post 3 still has pulling force, still, still can reach the technical problem to be solved in the present invention.For example:
When weight 5 freely swings, after vertical position, continue 40 degree of angle magnetic poles 3 of swing and topple over, use
Device of the present invention, fine rule 4 is after vertical position, and when continuing swing angle and being less than 5 degree, weight 5 just enters
Enter track 6, cause fine rule 4 to bend, pulling force disappearance, but magnetic pole 3 is still outwelled, this just illustrates, magnetic pole 3 is outwelled, no
Be because the deformation of fine rule 4 the reason for needing the time, but magnetic pole 3 outwell be one from slow to fast the reason for.
The tangent line of arc-shaped rail bottom 61 is horizontally oriented, and the position of arc-shaped rail bottom 61 is slightly below trajectory
51 minimum point, typically " summary " word, unclear statement., can but various equivalent modifications have been seen after this specification
To understand that this omits word, this slightly means this:Condition caused by elastic force has two necessary factors:1, contact, 2, there is deformation.
In actual mechanical process, it is difficult to accomplish only to contact still no deformation down to no elastic force, so, arc-shaped rail is most
The position of lower end 61 is slightly below the minimum point of trajectory 51, that is allows weight 5 behind equilbrium position, entrance circular arc as early as possible
Guide rail 62, then, the elastic force that fine rule 4 is applied by arc-shaped rail 62, fine rule 4 is then allowed not by elastic force, if allowing weight 5
When just past equilbrium position just and arc-shaped rail 62 generates elastic force, then, the elastic force of fine rule 4 can be because of having
The holding power of arc-shaped rail 62 and change.In other words:When weight 5 is just past equilbrium position, weight 5 and circle
Arc-shaped guide rail 62 does not contact, weight 5 just through equilbrium position, just as early as possible touched arc-shaped rail 62 and by circular arc
The elastic force that guide rail 62 applies.So explain, various equivalent modifications are it will be appreciated that omit the implication of word.If the summary also felt
Word belongs to unclear statement, can limit:The position of arc-shaped rail bottom 61 is lower 0.1mm- than the minimum point of trajectory 51
2mm。
Elastic card 64 and arc-shaped rail 62 do not contact, and this technical characteristic is such meaning:If elastic card
64 and arc-shaped rail 62 contact, result in:Weight 5 enters when entering 65 area encompassed of elastic card 64 and catch
Difficulty increases, once not being successfully entered, will slide and, then again pass by equilbrium position, such motion process is very
It is complicated.Meanwhile such motion process is nor the motion process to be studied, so, elastic card 64 and arc-shaped rail
62 are not contacted, and weight 5 can be allowed to be relatively easy into elastic card 64 and the area encompassed of catch 65.Weight 5 enters bullet
Property card 64 be exclusion open two elastic cards 64, elastic card 64 and arc-shaped rail 62 do not contact, be easy to weight 5 exclusion open
The two elastic cards 64.
Elastic card 64 respectively has a projection 641 relative, for preventing weight 5 from sliding in its inlet internal, and two is convex
Rise 641 horizontal range be less than weight 5 diameter.Weight 5 has poured elastic card 64 and catch 65 is surrounded due to inertia
Region, still, rethink when rolling down, speed is reduced, can not break through elastic card 64 again, also would not be along circular arc
Shape guide rail 62, which slides, to be come.It is therefore desirable to projection 641 is set.
Various equivalent modifications should know:In order to allow weight 5 accurately to enter elastic card 64, two elastic cards 64
It should live apart in the both sides of the movement locus of weight 5, and the length away from weight 5 is identical, that is to say, that:The center line of elastic card 64
Belong to the inswept perpendicular of fine rule 4.
The length of fine rule 4 can be 1m.
The present invention is simple in construction, beneficial to some dynamic (dynamical) problems are probed into, as complementary experimental provision, can accomplish reality
Phenomenon is tested with theory to be consistent.