Mystery For Scientific Minds

[dlaery]

I have a 1 lb counting scale.

I have several plastic boxes that weigh 0.3000 lbs each.

when I set the box on the scale to check the weight it reads 0.3000

if I put my hand above the box about 2 inches, the box gets lighter by 0.0010 to 0.0030

when I take my hand away it goes back to 0.3000

If I set a cardboard box on the scales without the plastic box and hold my hand over it, the weight does not get lighter.

If I put my hand over the scale with nothing on the scale, it does not get lighter, does not move at all

It has nothing to do with wind. this is a very sensitive scale and wind does affect it, but not in this case.

why does the scale get lighter when I put my hand over the box?

I don't know why, it is a mystery.

 

[mohawkman]

Static electricity on the plastic pulling towards your hand?

[RayburnGuy]

Static electricity on the plastic pulling towards your hand?

 

That would be my guess.

 

Ben

[Vodkaman]

X3 I would never have expected that though.

 

DAve

[JRammit]

Try rubbing a balloon on the carpet, then hold that above the plastic box on the scale... Curious if it gets even lighter??

[Travis]

It is static.  We utilize various methods to control the issue on all our balances.  From simple static strips, U shaped ionizer to pass samples through as placed on the balance, and faraday basket/cage to hold sample for weighing.   Last time Mettler Toledo came to demonstrate some balances part of the dog and pony show is demonstrating what you describe.  Low humidity also makes it worse.    

[dlaery]

thanks!

I suspected static but now I would say it confirmed.

I would be weighing these empty boxes to put tare weights on them and when I would reach to take the box off, the weight would change, and then when I would move my had back, it would go back to the original weight.

I just thought it interesting.