Is it possible to crush something with balloons Imagine an average party balloon. Little rubber ball you can inflate with a few breaths. If you had a box of deflated balloons that weighed a ton, and you dropped it on something, it would be crushed.
But what would happen if instead you took a box that contained exactly enough weight to crush an object (lets say, a watermelon) and you took the time to inflate each of those balloons (assume for the purposes of this that you have both the time, patience, and breath to inflate that many balloons manually. Also each balloon is exactly identical to every other balloon in the box, and they are filled to exactly the same size and pressure) and stacked them one on top of another in a tube with just the bottom balloon on the melon (so stacked 1 wide, N high). Would that still be enough weight to crush the watermelon? If not, how many more balloons would it take to crush the melon?
Imagine the same scenario, but this time instead of stacking the balloons perfectly atop one another, you just dump them into a pile on top of the melon. How many more balloons would you need to get the same force?
This question has no practical applications, it's just something that I've always wondered about. Intuitively it feels like 1 ton of balloons should be 1 ton of balloons, regardless of whether or not they are inflated. But at the same time, an inflated balloon falls slower than a deflated balloon (because its less dense and now closer in density to the air?). I assume there are a bunch of other factors I cannot even begin to comprehend how they would affect the process (the size difference between an inflated and deflated balloon, the springiness of an inflated balloon, etc.). Apologies in advance if this is too general for this board.
 A: Actually, your stack of inflated balloons could be slightly more effective in crushing something.
Inflating the balloons would increase their volume.  The effect would be:


*

*The balloon would have a greater cross-section, and would settle more slowly through the air.  This would be of no consequence once the balloons settled to a stop.  One tonne of inflated latex would still exert 10 kN force on the spot underneath.

*The balloons would have a larger volume, and hence a greater buoyant force created by the surrounding air. This would be completely offset by the requirement to include the air inside the balloon in the mass of the inflated balloon.


If the balloons were only partially inflated (staying limp) then the buoyant force and gravity on the included air mass would exactly balance, leaving a net zero effect.
However if the balloons were inflated with air to a pressure above the surrounding atmospheric pressure (tight stretched skin) and then tied off, the result is different.  The air in the balloon would be compressed to have a higher density than the surrounding air. The buoyant force would be less than the force of gravity on the compressed air, and the result would be an increased crushing effect...
As a rough indicator, the air in a one cubic metre balloon (big!) containing air at  $1.5 \times$ atmospheric pressure (high!) would mass about $1.84$ kg;  only $1.22$ kg would be balanced by buoyant force...
