Levarge .... Is that even physics?

[alex4478]

Hi,

I'm trying to remember the stuff I was taught at school about leverage. I understand the principle, but can't get my hear around this.

I want to build a device to weigh the contents of boxes. It needs to be able to measure in 1g increments. I could use my wifes kitchen scales. The items in the box are cables and in each box they would all be the same length, so the same weight. A different box may have a longer length cable and the weight would be different, but the cables would all be the same. So if I have one box with 3ft of cable and that box weighs 30kg, and each cable weighs 3kgs, then I'll have 10 cables in that box. Problem is that the boxes typically weigh 35-50kg, so they are too heavy for the kitchen scales (which have the required increments to measure the difference when adding one cable).

I was hoping to use a platform that the box would sit on that was longer than the box, so one end stuck out and I could then use that to 'amplify' the weight of the cables. But I have it wrong.

So how could I do this?

Many thanks for any help.

 

[CWatters]

Whatever you do it will be hard to measure 50kg to within 1g. Not many scales are accurate to 1 in 50,000 or 0.002%