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ammre
SILVER Member since Sep 2004

ammre

Member
Location: New Jersey

Total posts: 37
Posted:I got myself into a corner here... i agreed to spin poi with my juggling group at a museum... fine i'm cool with that...
BUT
somehow i have to relate it to science. The weekend is devoted to circus arts and their relation to science...

Unfortunatelly since i really have NO CLUE what i'm talking about (i move my wrists and it goes, simple as that! confused ) i have no clue how to explain. I've tried to read a few threads here but if i can't even figure it out how am i explaning it to little kids?

If anyone can help me? I need to make a quick writeup by friday and since i'm not using fire (indoors small area) i need to base it on the physics of spinning poi...


Thank you!


that which yeilds is not always weak.

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Jo


Jo

member
Location: Sheffield, England

Total posts: 517
Posted:Try relating it to planets orbiting the sun.

Or comets...

or maybe relate some moves to the pendulum of a clock?

Jo. smile


Educate yourself in the Hazards of Fire Breathing STAY SAFE!

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KaelGotRice
GOLD Member since Jul 2003

KaelGotRice

Basu gasu bakuhatsu - because sometimes buses explode
Location: Angel's Landing, USA

Total posts: 1584
Posted:Talk about angular momentum as well as tension. Then move on to conservation of momentum and how that relates to the movement of the poi.

To do: More Firedrums 08 video?
Wildfire/US East coast fire footage
LA/EDC glow/fire footage
Fresno fire

<img src="/ubbthreads/images/graemlins/ubbrollsmile.gif" alt="" />

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ammre
SILVER Member since Sep 2004

ammre

Member
Location: New Jersey

Total posts: 37
Posted:but i do't know any of that stuff.. that's the point.. i swing it it goes... i make it heavier, it goes a little easier, i make it lighter, it feels poopier, i put on tails it spins slower...
I dont' know WHY

I'll freely admit i'm really really stupid when it comes to this part.
jo- a nice idea but they want the physics behind why it does what it does.


that which yeilds is not always weak.

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Jo


Jo

member
Location: Sheffield, England

Total posts: 517
Posted:Check out this thread:

http://www.homeofpoi.com/ubbthreads/show...5/o/all/fpart/1
br>
really the best thing for you to do would be to google search for school/college physics / space classes on orbits and circular/pendulum physics.

Things like that are a good 'universal' interest to kids I think so good if you can relate it.

Also, these lessons will already be in tried-and-tested formats and I''m sure you could pick it all up in a couple of hours hard study.

Jo. smile


Educate yourself in the Hazards of Fire Breathing STAY SAFE!

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ammre
SILVER Member since Sep 2004

ammre

Member
Location: New Jersey

Total posts: 37
Posted:i read that thread before. It confused me more.
frown


that which yeilds is not always weak.

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MikeIcon
GOLD Member since Mar 2003

MikeIcon

Pooh-Bah
Location: Philadelphia, PA - USA

Total posts: 2109
Posted:Theres really a lot of science going on with poi. Perhaps you dont really know about it now, but it would probably be pretty interesting (and easy) to research it and find out. Theres all sorts of enegy and momentum being used, crazy forces at play and such. Learning the physics of poi may even teach you a move or two... Who knows? wink

Let's turn those old bridges we crossed into ashes.
We'll blaze a new trail,
and torch the rough patches.

-Me

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Whiffle Squeek


Whiffle Squeek

addict
Location: Hartford, CT USA

Total posts: 416
Posted:bah, physics, the bane of humanity...

(failed one of those tests today)

dip a dollar bill in alcohol, light it on fire, let the alcohol brn off, and explain that the dollar doesnt burn cause the alcohol burns at a much lower temp than the paper of the bill...

cept, that doesnt have much to do with poi...

but its still cool...


Educate your self in the Hazards of Fire Breathing STAY SAFE!

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Mr_Jedly
GOLD Member since Jan 2004

Mr_Jedly

member
Location: Perth, West Australia

Total posts: 195
Posted:It would take awhile to explain it here... but you'll have to look up some resources to find out what is happenning to poi when they spin.

here's some key terms to look for on the net:

centripetal force, momentum, velocity, acceleration, circular motion, gravity, tension, Free Body Diagrams, wind resistance / drag, angular momentum/acceleration/velocity, force, radius, diameter, circle, torque



I would suggest using free body diagrams to explain the forces acting on the poi, at different points in a circle. then showing what happens when letting go & throwing the poi across the room & explaining why that happens due to forces etc... hope it helps!



Edit: I probably would neglect technical drag explanations - just say that the air 'slows the poi down', requiring more effort to spin, depending on the poi shape.

EDITED_BY: raghkyre (1109838833)


We don't stop playing because we grow old,
We grow old because we stop playing.

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ammre
SILVER Member since Sep 2004

ammre

Member
Location: New Jersey

Total posts: 37
Posted:ahh see draghkyre, thank you that helped!

that which yeilds is not always weak.

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NYC


NYC

NYC
Location: NYC, NY, USA

Total posts: 9232
Posted:Yeah, if you look up some simple definitions of centripital force you should be well on your way.

Also, do the demo where you take a bucket of water and spin it while on a chain so that the water stays in the bucket.

Also, you can have the kids predict which way the poi will fly when you let it go. If you let it go at the top of the circle, most kids will think it will fly straight upwards but it actually flies at 90 degrees from that (So like straight forwards) because of the direction of the momentum at the time.

If you're cool, you find the force in the string by how fast the poi are moving and length of the poi and the weight of the poi.

Or, an easier one is, have a kid spin one as fast as they can for a set time. Then convert that to the actual speed of the poi. You can also see if a shorter or lighter poi is easier to get going faster. See if you can have a kid twirl a glowstick at over 100 miles an hour!

Hrm... lemme see how you'd do that.

1) Find the distance the poi goes in one rotation. That's 2*pi*(the length of the poi in feet)

2) Find out how many times the kid can spin the poi in 1 second (so like how many times he can spin it in 10 seconds divided by 10 or something).

3) Times the (Rotations per second in 2) by (Feet per rotation in 1) and you get how many feet per second the kid is spinning.

4) Times your "Feet per second" answer by 0.68 to find miles per hour. (Somebody double check me on that one.)

Example:
My glowstick was 1.5 feet long (18 inches) and I just spun it 72 times in 10 seconds.
1) The poi goes 9.42 feet per rotation.
2) The poi goes 7.2 rotations per second.
3) The poi goes 67.8 feet per second.
4) The poi goes 46 miles per hour.

Now my second trial:
2 foot poi, 60 times per 10 seconds.
1) 18.84 feet
2) 6 rotations/second
3) 113 feet/second
4) 77 miles/hour!

I bet I can get a longer poi going even faster! smile

*Someone smart please double check my math, I just woke up...*


Well, shall we go?
Yes, let's go.
[They do not move.]

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Gnor
BRONZE Member since Mar 2003

Gnor

Carpal \'Tunnel
Location: Perth

Total posts: 5814
Posted:Thanks NYC......anymore poi physics I would love to hear about. I do smart kids classes but my poi is better than my physics.

Is it the Truth?
Is it Fair to all concerned?
Will it build Goodwill and Better Friendships?
Will it be Beneficial to all concerned?

Im in a lonely battle with the world with a fish to match the chip on my shoulder. Gnu in Binnu in a cnu

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Mr_Jedly
GOLD Member since Jan 2004

Mr_Jedly

member
Location: Perth, West Australia

Total posts: 195
Posted:I don't do feet/miles in Australia... so i'm not sure of the coversions, but your theory is sound. :-)

After figuring the speed out, you could then find the force on the poi/your hand. You could use this to then make your own poi & find out whether of not the chain/string will break when swung around at those speeds!



eg:

You have the velocity. = v

Centripetal acceleration = a (acceleration inwards...towards your hand)

poi length = r (radius)

a = v*2/r

find the acceleration (at the bottom of the circle cause u gotta include gravity (9.8a m/s*2)- maximum tension)

Force(Newtons) = mass(of the poi) x acceleration.

find the capabilities of the string your using & see if it will break!

go outside, get 'weak' string & make it break!



Hmmm, this might be a lil bit hard for kiddies.

I also sound like a geek. bah.

ALso, I didn't look anything up for this... just from memory. Please correct me if I made a mistake!

EDITED_BY: raghkyre (1110253912)


We don't stop playing because we grow old,
We grow old because we stop playing.

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