Sciencemadness Discussion Board

Need a source for a special scale?

jgourlay - 28-2-2011 at 08:38

Gents, I know my search problem here has to stem from me not knowing the name of what I'm looking for. So, please let me describe it and you tell me what it is.

You know those scales sportsmen use to weigh fish? It's got a loop on one end to hang it from a rope, and a hook on the other to put through the fishes gills? The devices shows how far the weight pulls an internal spring and translates that pounds/kg force?

I need the "educational" version of that. I want to use it to suspend a weight from, and then show the difference in "weight" of the object in air, and suspended in water. I.e., I'm doing a bouyancy demo.

But I can't seem to find one of these anywhere except at the sporting goods store. The standard 25 fish scale is fine for a pulley demonstration using barbells, but worthless for a bouyancy demonstration in the 0-500 gram range.

Any suggestions?

bfesser - 28-2-2011 at 09:26

I have a pair of these, one from 0-250g (0-2.5 Newtons) the other from 0-500g (0-5 Newtons). Willing to trade, if you want them. Otherwise:

http://www.carolina.com/p2p/endecaSearch.do?pageName=Home+Pa...
http://cgi.ebay.com/4-Tubular-Spring-Scales-250-500-1000-200...

They're often referred to as 'spring scales'.

[Edited on 2/28/11 by bfesser]

peach - 28-2-2011 at 10:11

I don't know if it's the same in the US, but those are referred to as Newton (spring) meters in schools here.

They have Newtons on the scale, and are called Newton meters, to emphasis the idea that it's measuring a force and that kilos and grams are masses, that produce that force due to their interaction with gravity.


jgourlay - 28-2-2011 at 12:48

Thanks guys! That got me what I needed.

I'm trying to puzzle out how to make a groaner of an engineering joke out of "Newton meter" (the scale) vs Newtonmeter (torque). I'm thinking there's a "who's on first?" routine in there somewhere.