Helium is cheap, I pay about $34 for a bottle about 5’ tall; don’t remember the proper size of the bottle/amount of gas.
Helium is cheap, I pay about $34 for a bottle about 5’ tall; don’t remember the proper size of the bottle/amount of gas.
Actually, on thinking about it, here’s what I was trying to say:
Weight is a function of buoyancy, as well as mass and gravity.
Imagine an extreme case - a very large, thin-walled carton with a very small item inside.
We cut a hole in the side of the carton and insert a weather ballon, then start to inflate it with helium.
As it inflates, the mass of the parcel will decrease, because we are displacing air with lighter helium.
The weight will also decrease, because the mass is decreasing AND the buoyancy is increasing.
There comes a point at which the buoyancy exactly cancels the weight - the weight of the package effectively reaches zero, but the mass, while it reduces as a result of the displacement of air, can never decrease to zero.
Furthermore, for any size of item, we can add a suitably large package and such a large packet of helium that the weight is zero, but the mass will be significant
Which is what I was trying to say above - the ‘cost’ of laterally accelerating a package is significantly related to its mass(although rolling friction of the vehicle will also play a part), but it is possible to have two items that weigh the same, but have vastly different masses. - Weight and mass need not be proportional in a system where buoyancy is a significant factor.
Okay, I getcha. I’d buy that. I’ve factored “effective” net weight after buoyancy into a few recent posts myself
spingears and scr4, our helium testing for products here works like this: product is put into a vacuum chamber with line connected to filler neck. Chamber and product are exhausted. Helium is pumped under pressure into product. Any helium in vacuum chamber is detected by a mass spectrometer. This supposedly guarantees partially zero emmissions on the product. To localize leaks, product is removed from vacuum chamber, and left in atmosphere. Helium under pressure is pumped through filler neck. A wand is used to suck up air and deliver it to a mass spectrometer, and if helium is there lets us localize the leak.