Date: Fri, 17 May 2002 15:35:40 -0500

Author: James Braunsdorf

Subject: Re: Inertia Ball


Actually it works well to make both the support and the lower string loops
and use one end of a meter stick in the bottom loop. (I also put a foam ad
on the desk) I tell the students that one has to allow for etiher result and
that the stick is to keep my hand safe if the top string breaks first.

Then after offering the alternatives and taking a poll I usually strike the
meter stick sharply and snap the bottom string which usually loses in the
poll. after replacing that loop and pressing slowly to break the top string
I redo the quick pull part in a horizontal jerk with the kilogram just
sitting on the table and show that it doesn't even try to slide off the
table before the string breaks.

Jim Braunsdorf

>Alternatively, you could attach a second string that's longer, that will
>catch the ball as it falls.
>>>If I pull quickly, the lower one breaks.
>>>Do any of you know of any videos (especially high speed videos) of this?
>>>Also, can you suggest any related demos?
>>Remember to keep your hand out of the way! One way to avoid this is to
>>tie a the center of a wooden rod to the bottom string and push down on the
>>ends of the rod to break the strings. I had a serious bruise from doing
>>this demo once!
>>Mary Winn

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