Buoyancy is a function of gravity.
Without gravity, there would be no net "upward" force, because there also wouldn't be any net "downward" force.
Saying it doesn't make it so.
No, it didn't. It showed that air had weight to it.
Removing the air took the weight off of the scale, resulting in a net negative downward force on the scale.
No one wants to watch a video that's 2 hours long.
Please give a summary.
Gravity compresses the fluids. Fluids can't bear any shear stress, but that doesn't mean they don't experience shear forces.
Such forces are negligible (especially on a small scale), especially compared to the force exerted by a gas that causes it to expand.
Gravity causes the fluid pressure to be greater the further downward you go. Same with solids, for that matter (for example, here on earth, pressures at a depth of about 5 miles below the surface of the earth cause rock to deform like highly compressed, extremely stiff putty; in other words, a granite cliff on earth could never be higher than 5 miles high, because the rock near the bottom of the cliff would begin to become crushed, and pushed out from underneath the rock above).
Supra.
Right. There's nothing (heavier) to be pulled underneath it. More accurately, there is nothing underneath it to support it with upwards force.
Gravity is what is pulling it at 9.8m/s
2 downwards. (The "s
2" indicates acceleration, not linear speed.)
If gravity did not exist, then there would not be any downward force pulling the balloons to the bottom of the chamber.
Not quite.
They expand because there's nothing pushing back on the gas inside the balloon. It's a balancing act. When you blow up a balloon using your lungs, you are pushing air into the balloon with greater force than the atmosphere outside the balloon is exerting AND that the balloon itself is exerting.
The more air you put into the balloon, the more it expands, because the pressure inside the balloon is greater than the pressure of BOTH the balloon itself trying to shrink back to its normal size, AND the atmosphere pushing back against the outward pressure of the gas inside the balloon.
While you're holding the balloon, you are counteracting the force of gravity pulling downward on the balloon, and when you let go (assuming you've tied the opening), the balloon, since the pressures of the gas inside the balloon, the elasticity of the balloon, and the atmosphere, have equalized, removing your "upward" force of your hand holding the balloon causes the balloon to drop, since the downward pull of gravity is now greater than any net "upward" force.
If it's in a vacuum container, yes, it does, albeit briefly. It settles slightly denser closer to the bottom of the chamber, and less dense nearer the top of the chamber, because gravity is a compressive force on fluids, and because the further an object is from a gravity well, the less influence gravity has on it, and that includes atoms and molecules.
The "air" in the tub in the following video is a gas that is HEAVIER than air, and thus sinks in normal atmosphere. Watch how the demonstrator takes a cup of the "heavy air" and pours it into the foil "boat."
The boat is floating because, despite it being literally metal, the force exerted upon it by gravity is not enough to overcome the buoyancy provided by the heavy gas in the tub. This is because there is enough surface area for the gas to apply enough pressure to to keep it afloat, in the exact same way that normal boats float on water. If you were to ball up the foil boat, and drop it into the tub of the heavy gas, it would literally drop like a stone through air. That is because the balled up foil is a higher density than the air.
In a vacuum, a tank of air is heavier than a tank with nothing in it (vacuum).
