A somewhat relevant joke:
A mathematician, a physicist, and an engineer are discussing how much their poops weigh. Math man says he weighs himself before and after poop. Physics guy says he uses water displacement to accurately measure poop mass. Engineer says “i just shit on the scale.”
I recall doing an experiment in high school where we weighed a balloon that was blown up vs deflated. The one that was blown up weighed more, but by barely anything.
Assuming gas composition and compression and moisture and temperature of breath are the same as a fart, then yes you lose weight.
But methane is lighter than air, and there are so many other variables that it’s possible a fart would make you lighter. However that’s because of boyancy, you are losing mass plain and simple.
Lighter, but just barely.
You’d stay about the same, unless the gas you emit was substantially lighter or heavier than air. Methane should be lighter than air off the top of my head, but it’s not the only gas in the mix, so it’s hard to say without in-depth knowledge of the composition of farts, the subject’s diet, and ambient air temperature too, since the fart is gonna be at body temp but the atmosphere won’t.
if you put an empty balloon on a scale and then fill it up while it sits on there, would it get heavier or lighter?
it would press on the scale less but its mass would increase
Not really, the balloon gains volume at the same rate as it gains mass, so its buoyancy doesn’t change. Or at least it wouldn’t, if it weren’t for a a small detail: the air inside the balloon gets compressed, which makes it heavier for its size, making it gain more mass than it gains buoyant force. That means the scale would read an increase in mass, representing the extra amount of air that shouldn’t be occupying that space, were it not compressed.
Conservation of mass would prevent any outcome other than the scale showing you getting lighter.
No household scale would be precise enough for this experiment though.
I think that, theoretically, if someone’s flatus contained an abnormally high amount of lighter-than-air gases, like hydrogen and methane, they might get very slightly heavier. Having a gas like that inside of you would, I think, provide a bit of a buoyant force lifting you away from the scale that would make your weight read lower, and releasing that gas would sort of drop your full weight onto the scale.
In practice, methane and hydrogen are only part of a fart, and other gases and such in the mix are heavier than air, so at best you might break even.
Probably a few caveats to that about temperature and pressure and such, and it’s doubtful that anyone’s gut produces enough of the right kinds of gas for that to happen.
No, scales don’t measure mass but weight, it is completely possible to lose weight and have the scale show a larger number because of buoyancy. For example, grab a helium balloon capable of holding up a 1kg mass mid-air and the scale would show 1kg less than when you release it. This is very simple to understand, how much would the scale show for a 1kg object tied to that balloon? 0 of course, the object is not even touching the scale, and a slightly heavier object would only be making that slight weight difference of pressure on the sensors, not the remaining 1kg.
So conservation of mass has nothing to do with the question here. It’s all to do with whether farts are denser than air while inside your body.
whether farts are denser than air
They are.
Are you sure? It’s made mostly of Nitrogen, Hydrogen and Methane, all of which would be lighter than air because they’re at a higher temperature than the air outside.
