[Avodah] K'zayis as weight not volume?

[Gil Student]

I don't know what ROY says but R. Mordechai Willig also uses weight (I
will be"H be posting his calculations early next week). The real issue
is mass but weight can be used to calculate mass if you have the
appropriate conversion factor.

28 ccs of water weighs 28 grams. If something has the same density as
water and weighs 28 grams, then it has a mass of 28 ccs. Experiments
have shown that handmade shemurah matzah has approximately half the
density of water so 14 grams of handmade shemurah matzah has about a
mass of 28 ccs. Therefore, if you eat 14 grams (half an ounce) of
handmade shemurah matzah, you have eaten 28 ccs, which is a ke-zayis
according to ROY.

I believe an average handmade shemurah matzah weighs a over 2 ounces.
So ROY's shiur of ke-zayis is under 1/4 of an average matzah.




On 4/11/08, R Davidovich <raphaeldavidovich at gmail.com> wrote:
> I recently read a teshuva by R'Ovadia Yosef (Yechaveh Daat 1: 16) that gives
> the measurement for the k'zayis as a weight, not volume.  Instead of saying
> that the k'zayis is 28cc, which comes out to about  1/6 of a hand-matza
> according to Rabbi Heinemann's water-displacing  tests, ROY says that  it is
> 28 grams, which is the approximately the weight of half a hand-matza.  (With
> standard issue hand matza, you get about 8 matzos a pound, one slice is two
> ounces, or 56 grams.)
>
> I cannot figure out how ROY turned k'zayis and k'beitza into mass!
>
> Does anyone have sources or answers?
>
> --
> RD
>

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Gil Student,          Yashar Books
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