If I have a steel canister of helium and a balloon attached to the valve. If the helium is in the canister, the assembly stays on the ground. If I let the gas into balloon it floats. Why?
There is no change to the amount of energy, the gas is de-pressurised from the canister to the balloon and the density inside the balloon changes, but the overall weight stays the same.q I should know, I just can’t figure out why exactly.
Thanks
In: Physics
You answered your own question.
>the density inside the balloon changes,
Take a given total *mass* of helium, balloon, and tank.
Use it to fill up the space that used to contain the same *mass* of nitrogen, oxygen, argon, CO2, and other trace gasses that make up atmospheric air.
You now have something that experiences the same force due to gravitational acceleration as the air it’s displacing, and thus becomes able to float in mid air.
Displace another gram of air and your helium assembly will start rising.
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