YES NOPE9 <yes <at> nope9.com> writes:

>=20
> I was weighing pills and tried this setup to improve the scale sensitivit=
y.
> See photos here =3D=3D>
https://plus.google.com/u/0/photos/
102396176247280453443/albums/5882154251101853345?hl=3Den
> Max is 5000g says the scale legend.
> I put a hinge at one end of a bar and clamped it to a book.
> I put a styrofoam cup at the other end of the bar.
> I used a marker as a pivot point.   The bar does not touch anything else.
>=20
> #1  I used the tare function to zero the scale while the cup was at the e=
nd.
> #2  I measured in 9 pills and weighed them. ( 97 grams )
> #3  I added all the pills ( 90 ) and weighed them.  ( 969 grams )
>=20
> 969 /97 * 10 =3D .999   That was the best result I had.  My worst was 1.2=
8
when I was measuring smaller pills.
>=20
> What would be sources of error ? =20

There is no error.  Measurement with 90 pills is just more accurate, that's
all.  Statistically speaking, the number are most likely the same, although
one needs more measurements to prove it.=20

General sources or variability in this setup would be:
1. Friction, or, as somebody said - "sticktion";  The hinge does not look
like it will be moved by a small force;
2. knife-edge for the balance;
3. variability in tablet weight;
4. accuracy of the balances (often they have +/- 1 or 2% accuracy)
5. some force to move the marker (pivot point) since one end of the bar is
fixed and the other moves.=20

Hope this helps,=20

Sergey Dryga
http://beaglerobotics.com


--=20
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