[Diy_efi] measurement

[Bill Washington]

Dan,
    I don't mind the odd off topic - it helps keep the thinking flexible 
- Your approach sounds ok to me but I see your greatest challenge as 
getting your home balance to be accurately 10:1 - Here is how I would do it
1. get 11 new shiny pennies (minimum wear, therefore closest weight match)
2. on the short end of your balance place 10, on the long end place 1, 
and adjust the fulcrum position (or one arm length)  until it balances.
3. you now have a relatively accurate 10:1 balance - proceed from there.
Regards
Bill

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>I hope you guys don't mind this totally Off Topic, but you are one of my
>more scientific group of friends.
>
>I need somebody to review my physics/methodology below:
>
>Helping my daughter (16 yr old) with a science project.  She is testing two
>types of fertilizer by growing three equal size patches of grass, fertilizer
>A, fertilizer B, Control.
>
>Here's the real problem:  We need to measure VERY small amounts of granular
>fertilizer.  The grass patches are only .38 ft^2, one fertilizer amount
>comes out to .0213 ounces, the second comes out to .24 ounces.
>
>I don't know about you but I don't have that kind of scale around here.
>
>Here's my idea, please scrutinize, simplify, accurize...
>
>I am going to weigh 300 pennies tomorrow at work on an electronic postal
>scale, I think it reads out in 10ths of ounces.  If they read greater than 1
>ounce I should get 2 significant digits, possibly they will weigh more than
>10 ounces and we can work with 3 significant digits.  The assumption is that
>the pennies all weigh the same.  This will give me an accurate weight of one
>penny.
>
>Back home this weekend we will make a simple balance beam.  Since I don't
>have jeweled bearings, I'm thinking a simple string at the fulcrum will give
>as consistent results as anything.
>
>At the short end, say 10-to-1 ratio of lengths, I will have a hanging
>container with pennies.  At the other end I will have a plastic medicine
>bottle to hold the fertilizer.
>
>To zero the balance scale out I will add coins (any size) until the coins
>balance out the whole apparatus.
>
>Next, I will have to do the math as to how many pennies equal 10 times the
>weight of the desired fertilizer weight.  Place this measured amount of
>weight in pennies on the short end of the balance.  Next, fill the medicine
>bottle with fertilizer until it balances.
>
>Done, measured, accurate weight of fertilizer.
>
>Does all of that make sense?  It does to me.
>
>The hardest part will be helping her learn what we just did so she can
>defend her process on the project.
>
>Suggestions are appreciated.
>
>Dan Nicoson
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