A German waiter has set a new World Record by carrying 27 litre-sized glasses of beer: German waiter breaks beer-carrying record – video | World news | The Guardian
It got me thinking how heavy they must have been and if he could have made it easier by using really fizzy beer. Now I suspect the difference would be insignificant but my enquiring mind must know if fizzy beer is lighter than a non-fizzy variant? Is this a boring straightforward answer?
If it was foam (or actively foaming), it would be lighter than the same volume of equivalent non-foaming liquid, just because gases are less dense than liquids.
However, carbonated liquids are probably heavier than non-carbonated - because they contain additional dissolved gas.
And it is CO[sub]2[/sub], a gas which is heavier then air, and thus has negative buoyancy.
Nothing has negative buoyancy. CO2 in air has a buoyancy lower than its weight, but compared to the weight of the beer, both are going to be negligible.
Negative mass should have this property.
I do not see what is wrong with the concept of negative buoyancy with respect to a medium. Something that will float upwards, in water, air, or whatever, has a positive buoyancy in that medium, so something that will sink has a negative buoyancy. I am not aware of the existence of any concept of buoyancy that is not relative to a medium or that is necessarily always positive. What concept of buoyancy are you talking about? (I agree that the effect on the apparent heaviness of the beer in the OP’s scenario is going to be very small.)
When the CO2 is dissolved in a fluid, there’s not much point talking about its buoyancy vs air when it’s a pure gas - in the dissolved state, it’s doing something else.
ETA: by which I mean; the buoyancy of the gas-infused liquid vs air is a real (but minuscule) thing, but it can be calculated as a simple function of the container of gas-infused fluid as a whole (denser perhaps because of the added gas, but not directly because of the relative density of air vs CO2)
Easy enough to test. Buy 2 bottles of carbonated water. Open one and leave it out a couple of hours to go flat. Then weigh it. Then open the non-flat bottle and weigh that one.
buy 3 bottles of beer and open 2, drinking one in memory of that other ones untimely death.
It’s a sorry excuse for a beer drinker that will not drink a beer just because it’s a little flat.
I feel like variations between bottles and possible evaporation would make this data muddy.
I think the opposite approach might be better: use a force-carbonator like a SodaStream. Weigh a bottle of still water first. Force carbonate to maximum pressure. Weigh again.
My expectation is that it would be heavier, but possibly not enough to even detect.
Buoyancy is always relative to a medium, but it’s also always positive (unless you somehow had a medium with negative mass). The buoyant force is an upward force equal in magnitude to the weight of the fluid displaced by an object. A rock sitting on the bottom of a lake, for instance, displaces water and thus has an upwards buoyant force acting on it, with the result that it’s easier to lift that rock in the water than it is if you get it outside of the water. What you’re describing as “negative buoyancy” is just an object whose buoyancy is smaller than its weight, but it has that weight no matter what medium it’s in.