Date: Wed Aug 19 09:24:45 2009 Back to Contents ------------------------------------------------------------------------

Author: Paul Nord

Subject: Re: jumping disks



Thanks! Just want I wanted to know.


On Aug 18, 2009, at 6:40 PM, Irons, Stephen wrote:

> I just got some today too. I found that some of them were on a bit of
> a hair trigger at first but after using them a few times they broke in
> a little bit.
> I also put one relaxed on a hot plate, label side down and was
> satisfied to see it pop just as vigorously as it expanded from the
> heat than it does when it cools. I think this proves that it's
> bimettalic right?
> -Stephen.
> On Aug 18, 2009, at 4:50 PM, "Urs Lauterburg" > wrote:
>> Chuck,
>> I don't see a ''dimple'' in the center of the disks. In fact they are
>> pretty small in diameter (about an inch or so). In fact you don't see
>> well that they buckle a bit. Now, in this hot summer I can just take
>> one into my hand for a moment, then bend it the ''wrong'' way and set
>> it on a table. After 10 seconds or so the disk would take off. OK,
>> they only go up well if the hollow side is facing the table to give
>> it a center push when the disk suddenly bends. Why do the disks jump
>> higher when released on a penile? Is it because of the low air
>> pressure which sticks the disk a bit to the surface?
>> Anyway, again a simple demo but quite a number of aspects to
>> consider.
>> Regards
>> Urs
>> Urs Lauterburg
>> Physics demonstrator
>> Physikalisches Institut
>> University of Bern
>> Switzerland
>>> If these 'new' ones have a small 'dimple' poking up in the center -
>>> try this -
>>> Carefully balance the warm (cocked) disk on the point of a pencil
>>> NOW measure the height of the jump!
>>> This effect also works with the more mundane rubber poppers.
>>> Set the eraser end on the pencil on a table top for stability.
>>> On Aug 18, 2009, at Aug 18(Tue) 3:21 , Urs Lauterburg wrote:
>>>> Zeke,
>>>> Me too I have ordered a sample batch and got it a few days ago.
>>>> They seem to come from Sweden (not to be confused with
>>>> Switzerland). It seems as if somebody there has found out how to
>>>> make these things again. Mine seems to work OK. They jump about
>>>> 70cm or so. Did the old ones also jump about that high?
>>>> Nice little surprising things and a neat demo too
>>>> Urs
>>>> Urs Lauterburg
>>>> Physics demonstrator
>>>> Physikalisches Institut
>>>> University of Bern
>>>> Switzerland
>>>>> I received the jumping disks in the mail a couple of days ago
>>>>> (they may have come sooner but I was out of town).
>>>>> They work as advertised with the caveats listed on the website.
>>>>> They are fairly small and they have sharpish edges. They are
>>>>> fairly stiff and take some push to get to pop. In chilly San
>>>>> Francisco, it takes a long time to heat them up enough for them to
>>>>> hold their "loaded" position. I found that by keeping them in my
>>>>> pocket, they would be close to being warm enough without waiting
>>>>> an excessive time for them to warm up enough.
>>>>> I think that the rubber poppers probably teach conservation of
>>>>> energy better, but metal discs are more interesting in a material
>>>>> science kind of way.
>>>>> Zeke Kossover
>>>>> PS I also bought the Beta Pen
>>>>> which is a
>>>>> pencil that uses metal rather than graphite as its writing medium.
>>>>> As a novelty it succeeds and might make an interesting material
>>>>> science presentation, but it is a rather unpleasant writing
>>>>> experience.
>>>>> ----- Original Message ----
>>>>>> From: "Marc "Zeke" Kossover"
>>>>>> To:
>>>>>> Cc:
>>>>>> Sent: Thursday, July 30, 2009 3:48:06 PM
>>>>>> Subject: Re: [tap-l] jumping disks
>>>>>> From: Marsha Hobbs , sent: Thursday, August 31, 2006 7:18:02
>>>>>> PM
>>>>>>> A few years ago we gave away jumping disks at science
>>>>>>> presentations. I seem to recall they were from Edmund. Are
>>>>>> they available
>>>>>>> anywhere these days?
>>>>>> Yep, you are reading the date right. Marsha asked about jumping
>>>>>> disks three
>>>>>> years ago. As I recall, we didn't find any suppliers for her. As
>>>>>> I was wandering
>>>>>> around, I found some for sale at Grand Illusions, the fun Brit
>>>>>> toy site
>>>>>> I ordered some
>>>>>> today and am waiting patiently for them to come in.
>>>>>> Marc "Zeke" Kossover

From Wed Aug 19 09:24:45 2009