Re: Standard Kilogram

enders@xxxxxxxxxxxxxxxxxxxx wrote:

On Sep 19, 6:31 pm, "Ian Macmillan" <iand...@xxxxxxxxxx> wrote:
The recent report about a 50ug discrepancy in the comparison of the standard
1 Kg mass with its copies led me to wonder how such precision is attained,
50ug being 5 x 10^-9 Kg.

Can anyone describe the method of making such a comparison, and how the
degree of confidence in the result is estimated?

All the best
Ian Macmillan

I assume such a precision is possible by converting a measuring of
mass into a measuring of length.

Measuring a small signal within a big background is not clever. Null
the background to leave the net signal remaining, as with a balance
rather thana scale. The necessary mass differential sensitivity is
not unreasonable to obtain in hardware,

http://prola.aps.org/abstract/PRL/v89/i16/e161102
"Determination of the Gravitational Constant with a Beam Balance "
Phys. Rev. Lett. 89 161102 (2002)

Or, e-mail the folks and ask them how they determined the change.

--
Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
http://www.mazepath.com/uncleal/lajos.htm#a2

.

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