Background technology
Fine rule is fastened a weight and is moved in a circle at perpendicular, weight pulling force when minimum point is greater than gravity, and minimum point pulling force maximum-this is all easily by theoretical proof, want by this phenomenon of experiment performance, prior art discloses a kind of device studying circular motion: vertical panel, be positioned at vertical panel lower end for supporting the base of vertical panel, vertical panel is made up of iron plate, also comprise one to be made up of permanent magnet, shape is the magnetic post of column, magnetic post one end is adsorbed in vertical panel, magnetic post other end bolt fine rule, the upper end of fine rule is bolted to magnetic post, the lower end of fine rule hangs a weight.The using method of this device: the first step, rises certain altitude by weight, and: 1, make fine rule be in linear state; 2, fine rule departs from vertical position.Second step, release weight, weight starts to do the motion that shape is circular arc, that is: a part for circular motion.Select suitable off-position, such effect can be reached: at this position release weight, just magnetic post can be forgotten about it.Theoretical analysis is as follows: represent with T the pulling force that weight is subject to, and represent with G and represent the quality of weight with m by the gravity that weight is subject to, represent the speed of weight through minimum point with v, represent the radius of weight circular motion with r, derivation obtains
so, obtain minimum point speed v larger, the conclusion that pulling force T is larger.Explain with this experiment is auxiliary: magnetic post is forgotten about it, and illustrates that pulling force T force of gravity is large.Experimental implementation person recorded the video of this experiment, when playing video frame by frame, finds: magnetic post is not used in weight and is in minimum point and falls down, but obviously have passed through after minimum point, and magnetic post just.Experimental implementation person repeats experiment repeatedly, and all recorded video is also play frame by frame at every turn, all finds this phenomenon.This phenomenon and theory are not inconsistent.Do not found by people before this phenomenon: slow play just can observe this phenomenon.Outwell to magnetic post through minimum point from weight, approximately last 0.2 second.The time of 0.2 second, be approximately this device hang 1/8th of weight period of single pendulum, in this 0.2 second, the distance of weight process is approximately 2/3rds of amplitude, and the angle of fine rule and vertical direction is approximately 40 degree.So usually do not go out this phenomenon from observation the time, when slow play, the distance that can depart from equilibrium position from weight observes this phenomenon.
Strict, this experiment and theory are not inconsistent, and this experimental provision should not be used for the dynamic (dynamical) teaching of circular motion.In other words: a new device be researched and developed, the experiment that minimum point pulling force is greater than gravity can be demonstrated, and overcome above-mentioned defect.
Since research and develop new device, where is the problem will to know existing apparatus.Have two kinds of sayings: 1, the deformation of fine rule needs the time, and this time is approximately 0.2s, waits fine rule to complete deformation, and magnetic post is just subject to larger pulling force and is forgotten about it.2, magnetic post just starts to have toppled over through minimum point at weight, but the length of magnetic post falls short of, and after 0.2 second, just obviously finds out magnetic post and outwells.These two kinds of sayings sound all reasonable, if judge which kind of saying is correct with knowwhy, this is very complicated theoretical question.
About this phenomenon, also have other to explain, those explanations directly can be got rid of by theoretical analysis, so, just do not describe in this manual.
The present invention proposes a kind of device, this device can: 1, which kind of is correct to verify above-mentioned two kinds of sayings.2, overcome the weak point of existing apparatus, and reach experimental phenomena and the theoretical beneficial effect conformed to.
Embodiment
Accompanying drawing 1,2 is front elevation and the side view of prior art respectively.
Embodiment one
See accompanying drawing 3, be front elevation of the present invention, accompanying drawing 4 is side views of the present invention.Fig. 5 is side view of the present invention, and in Figure 5, a scope by dotted line, these scopes are exaggerated display in figure 6, and in other words, Fig. 6 is the partial enlarged drawing of Fig. 5.These accompanying drawings are expressed:
For the device of vertical plane dynamics research, comprise vertical panel 1, be positioned at vertical panel 1 lower end for supporting the base 2 of vertical panel 1, it is characterized in that: vertical panel 1 is made up of fire resistive material, vertical panel 1 is fixedly connected with one for adsorbing the adsorption plate 6 of permanent magnet, adsorption plate 6 is perpendicular for adsorbing that face of permanent magnet
Also comprise that be made up of permanent magnet, shape is a column magnetic post 3, magnetic post 3 one end is adsorbed in adsorption plate 6, magnetic post 3 other end bolt fine rule 4,
The upper end of fine rule 4 is bolted to magnetic post 3, and the lower end of fine rule 4 hangs a weight 5, and fine rule 4 is made up of the material being easy to blow,
Vertical panel 1 is provided with the hole 7 that runs through vertical panel 1 positive and negative, be provided with for flame to blow the first jet 8 of fine rule 4 after fine rule 4 departs from equilibrium position as early as possible in hole 7, and the flame direction of first jet 8 is: both perpendicular to vertical panel 1, again perpendicular to fine rule 4.
The position in hole 7 exists: the oblique upper of weight 5, and: close but do not coincide with the vertical curve at fine rule 4 place.
Explain: nozzle: first jet 8 of the present invention, second nozzle 9 all refer to the nozzle of flame, and the nozzle of flame belongs to prior art, the nozzle that such as following webpage is introduced:
http://detail.tmall.com/item.htm?spm=a230r.1.14.18.RhvunH&id=40119733829&ad_id=&am_id=&cm_id=140105335569ed55e27b&pm_id=&abbucket=5
http://item.taobao.com/item.htm?spm=a230r.1.14.279.RhvunH&id=16026116927&ns=1&abbucket=5#detail
http://item.taobao.com/item.htm?spm=a230r.1.14.212.RhvunH&id=39322048663&ns=1&abbucket=5#detail
http://item.taobao.com/item.htm?spm=a230r.1.14.145.RhvunH&id=38722875361&ns=1&abbucket=5#detail
http://item.taobao.com/item.htm?spm=a230r.1.14.34.SX1kPc&id=18445364256&ns=1&abbucket=5#detail
http://detail.tmall.com/item.htm?spm=a230r.1.14.59.SX1kPc&id=13974025302&abbucket=5
Because above-mentioned webpage is edited by the businessman of www.taobao.com, so cannot guarantee that above-mentioned webpage is always shown as nozzle, perhaps when businessman will edit this webpage is other commodity.
How to allow nozzle flame, belong to prior art, such as oxygen-acetylene burning flame, such as portable propane flame device, this is all prior art.The flame of nozzle ejection can have auxiliary equipment to regulate the size of flame, and make flame very thin, this is also prior art.
Using method: magnetic post 3 is adsorbed in adsorption plate 6, adsorption plate 6 can be fabricated from iron, first not flame, allow weight 5 depart from equilibrium position, and the shape guaranteeing fine rule 4 is straight line, and guarantees that fine rule 4 is parallel to vertical panel 1, then weight 5 is discharged, many experiments, finds this position: when this position release weight 5, weight 5 can forget about it magnetic post 3 just when circular motion.Mark this position.In order to the convenience stated, this position is designated as A position.
Pinch weight 5 with hand, make weight 5 be positioned at A position, then, allow nozzle flame, regulate the size of flame, flame firepower is concentrated, and flare is fine.
Release weight 5, makes fine rule 4 just after vertical direction, is just cut off by flare immediately.
Above presentation process full name video recording, then slow play, can see: fine rule 4 is just through vertical direction, fine rule 4 is just blown, meanwhile, the pulling force that fine rule 4 produces disappears, and magnetic post 3 still keeps horizontal direction to be adsorbed on adsorption plate 6, through the time of about 0.2 second, obviously observe magnetic post 3 and topple over.
Illustrate thus: 1, do this experiment by prior art and do not see that weight 5 forgets about it magnetic post 3 when minimum point, not because the deformation of fine rule 4 needs the reason of corresponding time, but because toppling over of magnetic post 3 is a process from slow to fast, the starting stage of toppling over, even if slow motion plays video, be also difficult to find that magnetic post 3 is obviously toppled over.Use device of the present invention, can prove: weight 5 when minimum point, pulling force truly have maximal value, and pulling force is greater than the gravity of weight 5.
The position in hole 7 exists: the oblique upper of weight 5, and: close but do not coincide with the vertical curve at fine rule 4 place.Near this word, normally unclear statement, but by above-mentioned introduction, various equivalent modifications is to be understood that: near referring to: fine rule 4, after vertical position, blows the position of fine rule 4 as early as possible.Why too lately can not blow fine rule 4? blow fine rule 4 because too late, when video slow play, still see that weight 5 obviously have passed through minimum point, magnetic post 3 is not still outwelled.Because the flame that nozzle sprays has certain width, so flame cannot just blow fine rule 4 when fine rule 4 is positioned at vertical direction.Reach such effect: 1, fine rule 4 is in the moment through vertical position, and flame burns continuous fine rule 4,2, and fine rule 4, after vertical position, just blows fine rule 4 as early as possible.After such explanation, the implication of various equivalent modifications is just appreciated that " close " two words, it is clear that " close " such statement just becomes.If that also feels is unclear near two words, can be expressed as: the position in hole 7 exists: the top of weight 5 equilibrium position, vertical direction distance weight 5 upper end 1-3cm, and: the horizontal direction distance vertical straight line 1-4cm in fine rule 4 place.
Why not cut off fine rule 4 with cutter? cutter no doubt can cut off fine rule 4, but cutter have also been changed the radius of weight 5 circular motion simultaneously, so cause pulling force to increase, magnetic post 3 is outwelled in this case, cannot say clearly radius reduce cause or magnetic post 3 topple over the result caused more slowly.
Various equivalent modifications should be known, and allow flame contact fine rule 4, instead of nozzle contact fine rule 4 itself.
Because nozzle temperature is very high, so vertical panel 1 is made up of fire resistive material.The ceramic tile of such as apparatus for building.Fire resistive material is not often attracted by permanent magnet, so vertical panel 1 is fixedly connected with one for adsorbing the adsorption plate 6 of permanent magnet.In order to ensure magnetic post 3 level, adsorption plate 6 can be allowed to be perpendicular for adsorbing that face of permanent magnet.Magnetic post 3 shape can be right cylinder.
The flame direction of first jet 8 is: both perpendicular to vertical panel 1, again perpendicular to fine rule 4.The flame of nozzle ejection, has the effect of certain force to fine rule 4, so blowing fine rule 4 perpendicular to fine rule 4 is the ways reducing error.
How first jet 8 is installed with in hole 7, is prior art, can be fixedly installed, and also can removably connect, and also can use hand-held welding torch, only allows nozzle stretch in hole 7.
Blowing fine rule 4 with flame, iff seeing this method, there is no creativeness completely.But the technical problem to be solved in the present invention is not how to cut off fine rule 4, but: 1, which kind of is correct to verify two kinds of sayings.2, provide the technical scheme that an experiment conforms to theory.Find a problem be never found, this is inherently creative.
Blow fine rule 4 by nozzle flame, fine rule 4 can be blown with the extremely short time.The most handy cotton thread of fine rule 4, it is almost instantaneously just to have blown that cotton thread runs into flame that nozzle sends.
Since the present invention says the nozzle of energy flame, so various equivalent modifications should be known, and wanting supporting time the present invention uses have the support equipments such as combustion gas generator, fuel gas transportation pipeline, gas quantity or amount of oxygen regulating device, and this is all prior art.
Embodiment two
See accompanying drawing 7, it is the technical scheme that the present invention is optimized by accompanying drawing 6.Also comprise: with the perpendicular through fine rule 4 be the plane of symmetry, with the symmetrically arranged second nozzle 9 of first jet 8, and the flame direction of second nozzle 9 is: both perpendicular to vertical panel 1, again perpendicular to fine rule 4.
Only blow fine rule 4 with a nozzle, there is a deficiency: the flame of ejection can allow fine rule 4 be subject to a very little momentum, the direction of this momentum is perpendicular to vertical panel 1 and away from vertical panel 1, even if like this, still allow a part of observer (student) statement into question, they think, are that flame have impact on the stressed of fine rule 4 to the momentum that fine rule 4 applies, then, fine rule 4 has forgotten about it magnetic post 3.Such saying has certain reason: because flame is applied with a momentum, although this momentum is extremely little really to fine rule 4.In order to overcome the momentum of this point point, another nozzle can be set, namely second nozzle 9, the flame that second nozzle 9 sends and the flame that first jet 8 sends intersect, in point of intersection, be exactly the position of fine rule 4 process, like this, fine rule 4 perpendicular to fine rule 4 direction, not to be subject to the momentum that flame applies along fine rule 4 direction.Certainly, two flame in opposite directions flame time to shorten the flame time as far as possible, in order to avoid equipment suffers damage.
How to fix second nozzle 9, belong to prior art, can support be used, also can use hand-held welding torch---certainly, hand will be held steadily when just passable.
Embodiment three
See accompanying drawing 8, the shape in hole 7 is: circular arc, and the hole 7 of circular shape, is positioned at the top of weight 5.The benefit that is designed with like this is exactly the position that can adjust flame point.And the center of circle of this circular arc is positioned at the junction of magnetic post 3 and adsorption plate 6, the radius of this circular arc is slightly less than rope length.Be slightly less than-these three words are normally unclear, but in the application, what be slightly less than means: the position that fine rule 4 is blown is preferably near the position of weight 5.Fine rule turns over identical angle, and the distance center of circle is far away, and the arc length of passing by is longer, if fine rule is blown in the position very near apart from the center of circle, fine rule deflection angle may be caused excessive.This understanding refers to the explanation of this instructions about " close " this word.
Each embodiment can reasonable combination use above.
Various equivalent modifications should be known, and the position that fine rule 4 is blown is preferably near the position of weight 5.
Cotton thread refers to the fine rule made with cotton, and cotton thread is easy to be blown.
Structure of the present invention is simple, is beneficial to and probes into more dynamic (dynamical) problems, as complementary experimental provision, can accomplish that experimental phenomena conforms to theory.