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This triple beam balance
reads to three decimal places,
which is important to remember.
We are going to be massing out
this copper rod.
The way we have that
happening is,
the balance itself
has been leveled out.
So the line that's on this
movable section is lined up
with the line here
just like a balance that
you would find at a
doctor's office.
After we are sure the
balance is zero'ed,
we'll place the copper bar
on the balance, and then
we will adjust these until
the balance resumes its
position at that neutral spot.
I've taken the balance
out to 40 grams;
what happens when we
cross over to 50 grams
is, the balance drops.
So what that lets us
know is that the copper
weighs between
40 and 50 grams.
We'll take it back to
40 grams, and we'll
adjust the single gram unit
until the balance slips over.
So we haven't added
enough weight yet.
Ok so 48 grams is too much.
So we'll go back to
47 grams,
and that's too much.
46 will put us over the top,
so this is between 46
and 47 grams,
so we'll be using
this fine adjustment
to put the balance
right in that neutral
position.
You can see that the
balance is lined up
in the neutral position,
and the way we would read
this is 46.404 grams.
So, this number
we would say that it is 40-
-6-point 4-
We've reached the .4,
but if you look carefully
at this notch you'll see
we haven't reached .41 yet
so our value is .40,
and then we look between
those two lines to see
how far it has moved
over and by my estimation
I would say
about a tenth of a spot,
so this mass would be
46.401 grams.
For massing our sample
our lines here need
to be directly lined up
with each other.