Author Topic: Physics!  (Read 8347 times)

JGherkin

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Physics!
« on: September 14, 2005, 05:08:48 pm »
Ok this could be seen as a cop-out, but I wanna do my piece of A2 physics c/wrk on diabolo, the only idea I have so far is to investigate into the effects of placement of mass on the diabolo and how this effects the length of time it takes to lose its speed to a stop.

Problems:
Any ideas as to how I could speed the diabolo up to a uniform speed each time I do the test with a different mass on it?

Any ideas as to how to apply the mass?  I was thinking of using something like plasterscene (sp??) but then this would introduce the problem of the mass not being entirely uniform is applied to the outside rim of the cups.


Also if anybody has any ideas as to other areas of the diabolo I could investigate please do share them as I can literally investigate anything as long as it has something to do with physics.

Cheers!  :D

JC

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« Reply #1 on: September 14, 2005, 06:22:37 pm »
I think you could use a defect CD.
Test it, you could bring a CD in the plastic hubs and also out.
Drill 4 holes into the CD, 90 degrees shift with the same hole circle. Repeat this in complete 3 times (near the mid, so far as it is possible - in the middle of the CD - and at the edge so far as it is possible).
You could buy round magnets (there different diameters, you must look what is the best for you, no big diameter but use heavy ones) with a thread inside, screw the magnets in one hole circle, test the time and so on ...
www.diabolonet.de - email to: diabolo-kits@web.de
MONOBOLOS, Henrys Circus, Vision and MB Finesse with round shaped axles

Tom Derrick

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« Reply #2 on: September 14, 2005, 07:46:04 pm »
I would suggest using something Finesse light kit shaped, and to add the weight, you can screw washers to the edge of it, which would mean that the weight distribution would be equal. Additions in weight wouuld be quite simple and uniform, too.
As for accelerating it to a uniform speed, you could colour inhalf of the rim, and use a stroboscope and accelerate the diabolo until the marking appears stationary.
There's probably a much simpler way to do it, but that's the best I can think of.

Chiok

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« Reply #3 on: September 14, 2005, 10:55:49 pm »
In the Finnish diabolo group video (I really can't remember how to spell it, sorry), they used a drill with a hex bit to speed it up and then just a quick jerk will pull out the bit.  This will require a Finesse of course and a 5mm hex bit.  As for adding weight, do as MB do and add weight kits.  Drilled metal washers would do the trick.

How about investigating gyroscopic motion and precession in conjunction with it?  A hex bit hooked up to a step motor with a variable power supply could set different speeds till stability is achieved.  Calculations would revolve (no pun intended) around angular momentum, moments from axle etc.  It's been a while but you could go that way, also investigate passive and active balancing (like with car tyres) how a balanced stationary object isn't always balanced when it spins.

Might be some more help from more informed people on this forum (Dr Matt perhaps?)  I did my A2 coursework on circular motion of a Hotwheels car around a loop the loop track and the velocity required for it to make the loop.

Hope you think of something, it's cool to investigate something interesting for a change.

Chiok
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University of Bath Juggling and Circus Skills

Dracodragon

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« Reply #4 on: September 15, 2005, 12:45:26 am »
Instead of doing how long it spins, maybe you can do something about (i think the gyroscopic force is the name) of the diabolo, and how that gives it more balance/stablility at a higher speed. here is a link to more info on gyroscopes. http://www.answers.com/topic/gyroscope

Or if you dont want to do that, you can maybe do how the 2d hpyerloop works or something. Timing how long a diabolo could go and adding mass to it will be a little more hard than those ones, but then again, its your project.
Go Draco with your Diabolo!
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Tahia

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« Reply #5 on: September 15, 2005, 09:06:56 am »
there is some informations abour physics on diabolo on the site of ludovich www.3diabolos.Com but it's in french sorry :D

JGherkin

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« Reply #6 on: September 15, 2005, 09:09:20 am »
Thanks for all your ideas so far, it took me a while to understand but I like JC's idea on how to add weight onto various points of the cup and if I continue with that line of investigation I may well use that idea.

I would definatly be up for investigating gyroscopic force and precision instead of the effect of mass on length of time it takes to slow down but the problem is still there about accelerating to a uniform speed.  Tom's idea sounds great...not entirely sure what a stroboscope is though, is it the same/similar to a strobe light?

Unfortuantly any ideas involving finesse I cannot use as I only own Circus' and a few lil crappy diabs.  If anybody has ideas about experiments to do with altering the diab I could easily perform these on the lil cheap ones I have.

Chiok

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« Reply #7 on: September 15, 2005, 01:09:36 pm »
Quote from: JGherkin
I would definatly be up for investigating gyroscopic force and precision instead of the effect of mass on length of time it takes to slow down but the problem is still there about accelerating to a uniform speed.  Tom's idea sounds great...not entirely sure what a stroboscope is though, is it the same/similar to a strobe light?
I meant "precession" which is different to "precision", but that might be a typo.  As for a stroboscope, vaguely like a strobe light.  If you put a good pen mark on the diabolo and start it spinning, at a certain velocity, the mark will become a line so you've gotta be switched on when you watch for that transition.  If you use the CD idea with holes, if there is more hole than material, at a certain speed the holes will appear stationary and above that will appear to spin in the opposite direction.  Like watching car hubcaps on the motorway.
Quote from: JGherkin
Unfortuantly any ideas involving finesse I cannot use as I only own Circus' and a few lil crappy diabs.  If anybody has ideas about experiments to do with altering the diab I could easily perform these on the lil cheap ones I have.
Can't borrow one...?

Chiok

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www.gravityvomit.co.uk - Gravity pulls down, we throw up.
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JGherkin

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« Reply #8 on: September 15, 2005, 04:16:47 pm »
Yeah sorry, I meant precession too, just a typo  :wink:   Had a quick chat to my physics teacher about the stroboscope idea and he said that sounds as though it would work great for measuring for a uniform speed.  Need to have more of a think about how I'm actually going to go about gaining any measurements for any kind of relationship analysis though.

As for borrowing a finesse I only know one person I live nearby to that diabolos and he owns Circus like me.  S`pose I could ask Guy if he'd be up for lending me his at juggling club one night...haven't seen him use them in months...then comes finding out if I know anybody with an appropriate drill and hex bit lol

nicoli

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« Reply #9 on: September 15, 2005, 11:30:21 pm »
this may be a little too complex but for the uniform speed thing, u could make a circuit with a spring switch inside the cup, when a certain speed is reached the centrafugal force would compress the spring, allowing two contacts to conect, completing the circuit and turning on an led or a buzzer. u may need several identical circuits in each cup to keep the uniform mass.
(that could be enough to be a project in its own right if u used spring constants and elastic potential energy)

garner

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« Reply #10 on: September 11, 2006, 08:28:43 pm »
sorry for the ancient bump but i have my own corusework coming up soon and i too wish to utilise the beauty and physics of my diabolo. i just wondered if any of you guys managed to pull of the coursework?

for myself i was thinking more along the lines of 'what forces and in what proportions act apon a diabolo to change it from a horizontal gyro to a vert gyro?' and  vice versa.

nezzybaby

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« Reply #11 on: September 11, 2006, 11:06:52 pm »
This is for physics a-level right?? i remember doing something random with paper aeroplanes when i did mine, seemed to be worth very little, as i hardly submitted anything and still got an A in physics.

My advice would be to work out how long the diabolo takes to stop spinning given different situations. As a control accelerate the diabolo, and leave it on the string till it stops spinning. Then try the same with different weights... best bet here would be to add washers on each side of the diabolo to increase the weight.

Next step would be testing grinds on different materials to see how long they can survive before losing speed, try a metal rod, wooden rod, and plastic rod. If you can form some kind of relationship betweeen thematerials and link them to frictional constants of the materials, you'll probably have a full marks kind of project.

just speed up as fast as you can, the accuracy required in these experiments is low, so as long as there is a considerable difference with the materials you grind on/weight of diabolo, then you should be able to generate results. Also these things are marked better if you have an anomylous result and explain it, so explaining that the diabolo isnt spinning at the same speed every time will probably earn you more marks than spinning it at the same speed every time.

If you manage to find out how fast you can get it spinning, can you pm me to let me know, im doing a very clever thing with diabolos for my electrical engineering dissertation, and a ball park figuer would be useful for me.

good luck and enjoy it, write up everything you do, no matter how minor it seems, the markers will get distracted by quantity and confuse it with quality, and always record anomylous results!!

nicoli

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« Reply #12 on: September 12, 2006, 12:16:29 am »
Quote from: nezzybaby
These things are marked better if you have an anomylous result and explain it, so explaining that the diabolo isnt spinning at the same speed every time will probably earn you more marks than spinning it at the same speed every time.


the diabolo not spinning at the same rate each time is not an anomoly, an anomoly is a result that doesnt fit the logical patern. if each diabolo has a diferent start rate there will not be a logical patern to the time they take to stop and thus there cannot be a result that doesnt fit the pattern.

also, to measure the time it takes for the diabolo to stop spinning on different sticks the diabolo would need to slow to a complete stop before falling off, which we all know it does not

mrpink

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« Reply #13 on: September 12, 2006, 12:16:49 am »
I have been playing with the idea to build a mathematical model that describes the 2D (or even 3D or even the 4D) shuffle. It would be described by some kind of partial diferential equation it seems to be a tricky one to work out the details so i never got much further than the idea ... Maybe not A level stuff but a good model culd be used for simulation software so there is even an aplication for this.

Shawn Fumo

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« Reply #14 on: September 12, 2006, 02:53:06 am »
The yo-yo physics booklets on this page might be something to explore. Many of the properties should be similar I'd think..
http://www.yoyoguy.com/yoyo/bookmag/

Crazy_Clown

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« Reply #15 on: September 12, 2006, 04:15:26 am »
Why dont you do something a bit simpler like finding the coefficient of friction of different strings and the axle and try to find the best string and say why it it the best?
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nezzybaby

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« Reply #16 on: September 12, 2006, 01:48:50 pm »
Quote from: nicoli
Quote from: nezzybaby
These things are marked better if you have an anomylous result and explain it, so explaining that the diabolo isnt spinning at the same speed every time will probably earn you more marks than spinning it at the same speed every time.


the diabolo not spinning at the same rate each time is not an anomoly, an anomoly is a result that doesnt fit the logical patern. if each diabolo has a diferent start rate there will not be a logical patern to the time they take to stop and thus there cannot be a result that doesnt fit the pattern.

also, to measure the time it takes for the diabolo to stop spinning on different sticks the diabolo would need to slow to a complete stop before falling off, which we all know it does not


the anomylous result will be for example one grind taking only 2 seconds when the averag is about 10 seconds, the explanation for teh anomoly is what i posted above, the marks come from explaining anomylous results.

Dunno about your diabolos, but mine tend to stay in a grind till they stop spinning, then they fall off a side and hit the floor. I reckon with metal hand sticks you get about half as much grinding time as on a carbon fibre stick, its very measurable.

garner

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« Reply #17 on: September 12, 2006, 04:19:53 pm »
thanks guys...but now i have the issue of how to keep the speed niform (within reason) and the only way i can think of is alocating time foracceleration and starting from no spin...what do you think?

the dynamics of a two diabolo shuffle seem interesting though but what forces are there? weight, the normal reaction force, friction of string, spinning of diabolo, momentum of diabolo, tension...anyone got a diagram?

Crazy_Clown

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« Reply #18 on: September 12, 2006, 06:22:26 pm »
Quote from: garner
the dynamics of a two diabolo shuffle seem interesting though but what forces are there? weight, the normal reaction force, friction of string, spinning of diabolo, momentum of diabolo, tension...anyone got a diagram?


There are a few more forces which not very easy to study, like drag of air, air resistance, etc.
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-Leo-

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« Reply #19 on: September 12, 2006, 06:28:02 pm »
Garner has the main forces to measure. Frankly, differences due to air resistances are going to be minimal.
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Relativity

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« Reply #20 on: September 13, 2006, 09:39:49 am »
I always thought it might be wicked to get a diabolo spinning and doing tricks in a room filled with purple smoke, so you can watch the diabolo pushing the air around it, and also the trails caused by suns and stopovers and orcits etc, reckon it'd work?
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The Vitamin Guy

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« Reply #21 on: September 13, 2006, 03:42:40 pm »
I guess propably not with poisonous gas.

But well seriously talking, why not?
The Vitamin Guy

garner

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« Reply #22 on: September 13, 2006, 04:07:46 pm »
is this true?: as long as you have perfectly balanced diabolos, perfect technique, frictionless string and an entirely hand(left, right or both) dominated shuffle you can do a 2, 3 etc shuffle without any spin.

this is pure theory obviously. i'm just trying to reduce things that may be an issue in my research.

The Vitamin Guy

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« Reply #23 on: September 13, 2006, 04:42:06 pm »
I believe that it's possible. Well, in theory ofcourse. Correct if I'm wrong.
The Vitamin Guy

Jussi

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« Reply #24 on: September 13, 2006, 05:40:43 pm »
Quote from: garner
is this true?: as long as you have perfectly balanced diabolos, perfect technique, frictionless string and an entirely hand(left, right or both) dominated shuffle you can do a 2, 3 etc shuffle without any spin.


well, if you have perfect technique you dont need frictionless string or perfectly balanced diabolos.. you can do suffle with anything like kettles and hamsters and phones and bottles? the physic wont make limits - but there is reason why diabolos shape is like it is and reason why it spin.. you know :)

Mithew

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« Reply #25 on: September 18, 2006, 11:33:59 pm »
Quote from: Relativity
I always thought it might be wicked to get a diabolo spinning and doing tricks in a room filled with purple smoke, so you can watch the diabolo pushing the air around it, and also the trails caused by suns and stopovers and orcits etc, reckon it'd work?


This seems a big off topic, but if you wanted to do that wouldn't a smoke machine be easier and work almost as well?  Or dry ice or something similar...
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