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Heat Conductivity - Ball and Ring

Posted: 13 May 2011, 14:42
by sunray18
Some of our ball and ring sets are no longer working.. in other words, the ball DOES NOT go through the ring when it is all cold.
HOD gave them to me to fix.
?????????????? HELP please

Re: Heat Conductivity - Ball and Ring

Posted: 13 May 2011, 14:45
by dime
Buy new ones. :wink2:

Re: Heat Conductivity - Ball and Ring

Posted: 13 May 2011, 14:48
by kimmy
Tell your HOD that he needs new balls and any ideas??????? :cheesy: :cheesy:

I would just be purchasing new ones. :thumbup:

Have a good weekend

KIMMY

Re: Heat Conductivity - Ball and Ring

Posted: 13 May 2011, 15:38
by RosalieM
you could try using them the other way - stick the ball in a beaker of ice, salt and some water to make it really cold and see if it shrinks enough to fit through? Same demo in reverse! Otherwise, yep, buy new ones!

Re: Heat Conductivity - Ball and Ring

Posted: 13 May 2011, 16:51
by Lyn
Just sandpaper the ball to get rid of the grungy buildup and sandpaper the inside of the ring as well. Make sure the balls drop through the rings easily while cold. Sandpaper them till they do. I have used a coarse sandpaper and then a medium grade sandpaper. Wet and dry paper could also work. If that doesn't work then a metal file should do the trick.
Lyn.

Re: Heat Conductivity - Ball and Ring

Posted: 16 May 2011, 09:42
by sunray18
"""Tell your HOD that he needs new balls and any ideas??????? """"
Wish I could but HOD is female!!!

I was just asking a physics teacher how to fix them and a casual teacher [ older female] walked in, and said with a tone in her voice that said she thought I was an idiot -
"JUST get a machine and machine the hole out".. then she walked out.. :redcard:
I don't have a 'machine'. what machine? I am not a TAS assistant! :redcard:
Now does anyone else keep one of those machines in their prep rooms just in case you need it?
I am a little miffed right now ... the physics guy said 'Get some new ones'..
seems that is the SANEST thing to do!
thank you all!

Re: Heat Conductivity - Ball and Ring

Posted: 16 May 2011, 09:58
by Loopy
Hmmm... sounds like the casual needs some machining! :cheesy:

Re: Heat Conductivity - Ball and Ring

Posted: 16 May 2011, 11:03
by smiley
Umm, why can't you try heating the ring, to see if it expands enough to let the ball thru? In other words, do the demo in reverse! :thumbup:

Re: Heat Conductivity - Ball and Ring

Posted: 16 May 2011, 11:13
by Ian
smiley wrote:Umm, why can't you try heating the ring, to see if it expands enough to let the ball thru? In other words, do the demo in reverse! :thumbup:
Just for the record, back in the "Olden days" when I was a teacher, they actually made them so that the ring was heated and expanded enough so that the ball would fit through. Trouble was, if the ring cooled just a bit so that the ball was only half way through when it shrunk, then the ring and ball would become PERMANENTLY attached to each other! Then you WOULD have to throw them away and get new ones! Bye the way, that is exactly the way that metal tyres were fitted to Wagon wheels (not that I can personally remember that! even if my great grandpa was a blacksmith)

Ian :)

Re: Heat Conductivity - Ball and Ring

Posted: 16 May 2011, 11:48
by sunray18
Ihave just had a discussion with some teachers about this - and some are adamant that the ball only goes through the ring whent he ring is heated, and another few are just as certain that the ball only goes through the ring when the ring is cold!
I quietly left the staff room with a polite discussion going on... :cheesy:
I never thought a simple prac would cause such dissension!!! :cheesy:

Re: Heat Conductivity - Ball and Ring

Posted: 16 May 2011, 12:09
by smiley
Yeah I'm right there with you Ian - I remember when you heated the ring not the ball AND I also remember the subsequent problems. So maybe Sunray, maybe your equipment isn't broken - it's just the other type. Hardly matters, as long as you can show the principle.

Re: Heat Conductivity - Ball and Ring

Posted: 16 May 2011, 13:35
by Ocker
When I first started to read this I thought
the ball is not supposed to go through the ring until you heat the ring then it will drop through :w00t:

Re: Heat Conductivity - Ball and Ring

Posted: 17 May 2011, 09:16
by sunray18
ahh Ocker - how can a simple prac that is done ONCE in a student's life be so difficult!

Re: Heat Conductivity - Ball and Ring

Posted: 24 May 2011, 10:09
by J
I bought some new ones some time ago. Some of the balls passed through cold and some not. I tested them to make sure they worked one way or the other, told the teachers about it and left them to sought it out for themselves. No complaints so far.
J

Re: Heat Conductivity - Ball and Ring

Posted: 24 May 2011, 10:36
by cheltie
We also have some that work each way so I let the teachers sort it out.
One teacher however put all the hot ones in a plastic tray to send back to the prep room.
I now have a couple so deeply melted into the plastic tray I can't get them out.
Didn't seem to occur to her that hot metal might melt the plastic!!!
Helen

Re: Heat Conductivity - Ball and Ring

Posted: 24 May 2011, 10:49
by smiley
Aaaahhh - but you were expecting logic, I fear. Well, guess you won't do that again will you!

Re: Heat Conductivity - Ball and Ring

Posted: 24 May 2011, 14:09
by cheltie
Yes, it was silly of me to think the teacher would think about what they were doing.
You're right I won't do that again.
Helen

Re: Heat Conductivity - Ball and Ring

Posted: 25 May 2011, 10:01
by SGG
Our ball and ring sets keep falling apart (chain breaks) and to make matters interesting - they are ALL different sizes. Also some are made for the ball to go through when cold and some aren't! :crazy: So every time they are used I have to "match the parts" and put them back together.
Sue G

Re: Heat Conductivity - Ball and Ring

Posted: 25 May 2011, 11:10
by dime
The chains used to be the bane of my existence; always trying to repair them. In the end I chucked them all out. Eventually I bought new ones that are separate. One handle with the ring on it and one handle with the ball on it. So I guess they are interchangeable. No complaints yet, only melted trays when the little dears put them back hot. Come to think of it, I should only send them out in a metal one.

Re: Heat Conductivity - Ball and Ring

Posted: 25 May 2011, 14:26
by Labbie
Where do you purchase the separate ones from? Like the idea of a metal tray.

Well done =D> =D> =D>