CN2113531U - Rotating inertia experiment demonstrating instrument - Google Patents
Rotating inertia experiment demonstrating instrument Download PDFInfo
- Publication number
- CN2113531U CN2113531U CN 92211148 CN92211148U CN2113531U CN 2113531 U CN2113531 U CN 2113531U CN 92211148 CN92211148 CN 92211148 CN 92211148 U CN92211148 U CN 92211148U CN 2113531 U CN2113531 U CN 2113531U
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- CN
- China
- Prior art keywords
- big disk
- wheel hub
- moment
- aluminium matter
- inertia
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- Testing Of Devices, Machine Parts, Or Other Structures Thereof (AREA)
Abstract
The utility model relates to a rotating inertia experiment demonstrating instrument, belonging to the technical field of the experimental instrument for teaching the physics. The existing experimental instrument for measuring the rotational inertia has the defects of large friction torque, low measuring accuracy, inconvenient operation, etc., and is not accurate in theoretical calculation of the rotational inertia according to the structure. The utility model comprises a large circular disk made from the aluminum, a wheel hub, a bearing, a bracket, a scale, a driven poise and a small cylinder. The utility model is convenient in operation, stable reliability, high precision, simple structure, general theory and exercise, uneasy abrasion and convenient maintenance. The relative error of the measuring value of the rotational inertia and the value of the theoretical calculation is smaller than 1%.
Description
The utility model is the Experiment of Moment of Inertia demonstrator, belongs to the physics teaching experiment instrument field.
According to the Rigid Body in Rotation With law, the experiment that utilizes the dead axle of rigid body to rotate the moment of inertia of measuring rigid body is the important basic experiment of general physics teaching.The moment of friction that how to reduce in the rotation is to improve the key point of experimental precision.Traditional method is to adopt the needle point bearing.Adopting the order of magnitude of the moment of friction (at this moment minimum) of device when bearing table is unloaded of needle point bearing is 10
-4Newton meter (is about 4 * 10
4Newton meter); The relative error of measuring moment of inertia is about 1%～2%.The shortcoming of needle point bearing is easy wearing and tearing, and after the bearing wear, the moment of friction of apparatus increases, and unstable, thereby causes the decline of Instrument measuring precision.In addition, change bearing neither one thing easily.
The eighties, U.S. Physical Education Teacher has designed a kind of device that uses ball bearing to measure moment of inertia.In this device, people have adopted a kind of new measuring method: obtain moment of friction according to the principle of work and power, deduct moment of friction by driving moment again and obtain clean rotating torque, obtain moment of inertia according to net torque and angular acceleration then.The physical thought of this method is clear especially, to the very enlightening property of teaching.Can also calculate the moment of inertia of rigid body according to parallel axis theorem with this device.This experimental provision is taken in " U.S. Physical Education Teacher association instrument sports " (AAPT APPARATUS COMPETITIONENTRIES, 1984).Relative error between the experiment value of the moment of inertia that records in this way and the theoretical calculation value is 10%, and as seen its experimental result is desirable not enough.The main cause that error occurs has three: one, ball bearing selected in this device bigger, thereby moment of friction is also bigger; Two, be to utilize bolt that two additional roundels are fixed on the traffic cycle in this device.The moment of inertia of this bolt arrangement is difficult to accurate calculating.In addition, fix roundel in this way, operation is also inconvenient; Three, the design of rotary disk does not reach optimum dimension as yet.
In view of this, in design during this new instrument, the square and improve the mode of fixing two roundels of making every effort to reduce friction, simultaneously, the size of selector disc correctly also.
The purpose of this utility model is the shortcoming that overcomes prior art, develops a kind of experimental apparatus of Measuring Moment of Inertia Using of novel function admirable.
The utility model Experiment of Moment of Inertia demonstrator is made of aluminium matter big disk, and the wheel hub of aluminium matter is equipped with at the center of disk, inlays a ball bearing in the wheel hub, is drilled with a hole on the sidewall of wheel hub, drives counterweight usefulness for binding.The same diameter in big disk upper edge center of circle symmetria bilateralis be drilled with two equal-sized circular holes, each circular hole all can directly embed one with the consistent aluminium matter small cylinder that highly equals big disk thickness of circular hole size.Bearing Installation is fixed by lock nut on the wheel shaft made from brass, and big disk can freely rotate around wheel shaft.The wheel axle horizontal is installed on the vertical rack that has triangle base, and levelling bolt is housed respectively on the triangle base, regulates them, can make wheel shaft be in horizontality.Vertically on vertical rack, fixing a scale that has scale below the big disk, for the usefulness of measuring the position that drives counterweight.Drive counterweight and be fixed on fine rule on the pore of wheelboss side wall, for the usefulness that produces driving moment.
Figure 1 shows that the front elevation of big disk and scale and driving counterweight.Figure 2 shows that the side view of big disk.The 1-big disk; The 2-small cylinder; The 3-wheel hub; The 4-ball bearing; The 5-scale; The 6-wheel shaft; 7-drives counterweight m; The 8-fine rule; The 9-lock nut;
φ
1-big disk diameter; φ
2-small cylinder diameter; ι-big disk thickness; The r-hub radius; h
1The height that-counterweight falls; h
2The height that-counterweight gos up; The h-counterweight is made a certain suitable distance that uniform acceleration falls.
Range of size: φ
1=150mm-300mm; φ
2=50mm-70mm; ι=6mm-15mm; R=40mm-50mm; Scale: 50cm-80cm; Ball bearing: 20
#-23
#: comprise 23
#Counterweight m=15g-50g.
The rotary large wheel dish, it highly is h that counterweight is risen to
1The position.Counterweight and big trochal disc are remained static, counterweight is fallen.After counterweight dropped to minimum point (0 position), because the rotator inertia of wheel disc, counterweight was thus lifted to h again
2The place.Because the cause of overcome friction square work done, make h
2＜h
1
Provide a driving torque by the fine rule on wheel hub to big disk
ι
1＝Tr （1）
T is the suffered tension force of fine rule in the formula, and r is the radius of wheel hub.If when the height that counterweight m descends is h (this moment, counterweight slowed down as yet), be 1 corresponding fall time, and suppose that the acceleration a that m falls is a constant, then has
a＝2h／t
2（2）
And the angular acceleration β=a/r (3) of rotor
Tension force T is
T＝mg－ma （4）
G is an acceleration of gravity in the formula.
Can obtain the average friction torque tau according to the principle of work and power
fWhen m from height h
1After the place drops to minimum point, rise to height h again
2In the process at place, the angle of wheel disc spins is
θ＝ (h
1+h
2+(π-2)r)/(r) （5）
The merit that rotor overcome friction square is done is
τ
fθ＝mg（h
1－h
2） （6）
So τ
f=(mg (h
1-h
2) r)/(h
1+ h
2+ (π-2) r) (7)
Clean rotating torque is
τ＝τ
r－τ
f
＝mrlg (2h
2+(π-2)r)/(h
1+h
2+(π-2)r) - (2h)/(t
2) （8）
The moment of inertia of rotor is
T
Survey=τ/β=τ r/a
＝ (mr
2t
2)/(2h) 〔g (2h
2+(π-2)r)/(h
1+h
2+(π-2)r) - (2h)/(t
2) 〕 （9）
According to formula and the parallel axis theorem of calculating moment of inertia, can obtain the moment of inertia T of rotor exactly
Meter(two kinds of situations when comprising big disk embedding two cylinders and not embedding cylinder).
According to I
SurveyAnd I
MeterCan obtain
(△ l)/(l
Meter)=(l
Survey-l
Meter)/(l
Meter)=% (10)
According to (1), (4), (7), (8) formula, can obtain τ
1, τ
fAnd τ, and obtain
ι
f／ι＝ ％ （11）
The utility model embodiment is: the big disk diameter is 220mm; The small cylinder diameter is 60mm; Big disk thickness is 8mm; Hub radius is 48mm; Meter ruler length is 70cm; Ball bearing is 23
#Driving the counterweight quality is 20 grams.
The utility model has been innovated design: open two circular holes and inlay small cylinder on big disk, both be convenient to operation, can accurately calculate the theoretical value of the moment of inertia of disk again; Select small size ball bearing, make moment of friction reduce greatly; Reasonably the size of selector disc had both reduced moment of friction, had increased moment of inertia again, thereby can improve the measuring accuracy of time.
The utility model stability of instrument is good; The precision height; Simple in structure; Easy to operate: theoretical utilization is comparatively comprehensive; Not easy to wear, easy to maintenance.Moment of friction≤1 * 10
4Newton meter; The measured value I of moment of inertia
SurveyWith calculated value I
MeterBetween relative error
(△ l)/(l
Meter)=(l
Survey-l
Meter)/(l
Meter)＜1%.
Claims (8)
1, a kind of Experiment of Moment of Inertia demonstrator, comprise aluminium matter big disk, A-frame, scale and driving counterweight and two aluminium matter small cylinders, disc centre is equipped with aluminium matter wheel hub, ball bearing is housed in the wheel hub, ball bearing is installed on the wheel shaft, big disk is freely rotated around wheel shaft, wheel shaft is horizontally fixed on the A-frame, driving counterweight is bound on the little pore of wheel hub side with cord, scale vertically is fixed on the big disk below, it is characterized by that the same diameter in big disk upper edge is monosymmetric in the center of circle two equal circular holes, two aluminium matter small cylinders can directly embed in the circular hole.
2, as 1 described big disk, its diameter length is between 150mm to 300mm.
3, equate as 1 described big disk, its thickness and small cylinder height, between 6mm to 15mm.
4, as 1 described ball bearing, its model between the 20# to 23#, comprise 23#.
5, as its radius length of 1 described wheel hub between the 40mm to 50mm.
6, as 1 described aluminium matter small cylinder, the Circularhole diameter on the corresponding big disk of its bottom surface diameter, scope is between 50mm to 70mm.
7, as 1 described driving counterweight, its quality is between 15 grams restrain to 50.
8, as 1 described scale, its length between the 50cm to 80cm.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 92211148 CN2113531U (en) | 1992-01-24 | 1992-01-24 | Rotating inertia experiment demonstrating instrument |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 92211148 CN2113531U (en) | 1992-01-24 | 1992-01-24 | Rotating inertia experiment demonstrating instrument |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN2113531U true CN2113531U (en) | 1992-08-19 |
Family
ID=4956190
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 92211148 Granted CN2113531U (en) | 1992-01-24 | 1992-01-24 | Rotating inertia experiment demonstrating instrument |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN2113531U (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104123865A (en) * | 2014-07-02 | 2014-10-29 | 齐齐哈尔大学 | Rotational inertia measuring and demonstrative experiment device |
| CN104346977A (en) * | 2014-08-19 | 2015-02-11 | 浙江工业大学 | Rotary inertia teaching instrument |
| CN104361792A (en) * | 2014-11-10 | 2015-02-18 | 皖西学院 | Rotational inertia measuring device |
| CN109186856A (en) * | 2018-10-30 | 2019-01-11 | 中国航发哈尔滨轴承有限公司 | Start the scaling method and measurement method of measurement of friction torque instrument pressure value |
-
1992
- 1992-01-24 CN CN 92211148 patent/CN2113531U/en active Granted
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104123865A (en) * | 2014-07-02 | 2014-10-29 | 齐齐哈尔大学 | Rotational inertia measuring and demonstrative experiment device |
| CN104346977A (en) * | 2014-08-19 | 2015-02-11 | 浙江工业大学 | Rotary inertia teaching instrument |
| CN104361792A (en) * | 2014-11-10 | 2015-02-18 | 皖西学院 | Rotational inertia measuring device |
| CN109186856A (en) * | 2018-10-30 | 2019-01-11 | 中国航发哈尔滨轴承有限公司 | Start the scaling method and measurement method of measurement of friction torque instrument pressure value |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C06 | Publication | ||
| PB01 | Publication | ||
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| C19 | Lapse of patent right due to non-payment of the annual fee | ||
| CF01 | Termination of patent right due to non-payment of annual fee |