A fast fast

[Adrian Hon]

Originally posted by snoopy369

Weight = Pull of gravity on a mass = proportional to mass when gravity is constant

Density = Mass over volume

Density is not relevant to weight. As stated above, unless the fart is replaced by a greater mass of air - which it, generally, is not - you are expelling mass/weight.

OK, so imagine you are standing on some scales with about one hundred helium balloons strapped to you. Clearly the balloons, plus the helium inside them, add to your mass - but they're lifting you up, so the weight the scales report is actually reduced. Now, you let go of the balloons and of course your weight will go up. Ditto for helium, or any other lighter-than-air gas, that is somehow attached to you.

Amazingly, someone has written a lot about this (I searched for 'fart weight down' on Google):

http://www.helium.com/tm/522270/weight-farta-lawyer-recently

I notice that this makes a distinction between weight, and weight reported by a scale. I am obviously talking about the latter, since that's what was used in the original 'experiment'. But I agree that by your definition, weight has in fact gone down.

[Straybow]

Farts are predominantly CO2, which is denser than air.

[Adrian Hon]

I wasn't the one who claimed fart gas was lighter than air, but according to Wikipedia (not the best source, I know):

http://en.wikipedia.org/wiki/Flatulence#Composition_of_flatus_gases

The major components of the flatus by percentage are:

* Nitrogen - 20% - 90%
* Hydrogen - 0% - 50%
* Carbon Dioxide - 10% - 30%
* Oxygen - 0% - 10%
* Methane - 0% - 10%

Both nitrogen and hydrogen are lighter than air.

Yes, I know this is a silly debate.

[Cort Haus]

Silly, but funny.

[Omni Rex Draconis]

An amusing thought experiment, indeed.

The reading on your bathroom is determined by three factors: your mass, the local pull of gravity, and your volume.

Your mass is going down when you expel the gas, so your weight will drop.

Local gravity should not be changing, we hope.

Your volume determines how much air you are displacing. Assuming you do not actually shrink when passing gas, then the lifting force of buoyancy will remain the same.

That would change, however, if you are so mutated that you actually store great quantities of flatus stored in swollen sacs around your body. It would then depend more on the pressure at which the gas is stored.

If it is squeezed until its density exceeds that of the air around you, then you will get lighter as you expel the gas and your flatus sacs shrink.