Someone reminded me of that wife’s tale where it takes a crane to remove a mattress from a pool and that itself reminds me of how sometimes removing certain floaties from the pool could be needlessly hard at times while super easy other times. Why does this happen?
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I believe it would be because water is more dense than air, obviously you can’t compress water, so when you go to grab something you are also grabbing the water, which will slip out of your hand bringing whatever you were attempting to grab with it.
Because water is over 800 times more dense than air and it sticks to things better than air. That density means you encounter more resistance when you travel through it because you have to move more mass out of the way. That’s why boat propellers are so small compared to aircraft propellers. An aircraft has to move 800 times more air to generate the same amount of force in water.
A mattress is mostly air. Lifting a mattress out of water would usually involve the mattress being soaked. A soaked queen size mattress weighs about one metric ton.
Removing a floaty from a pool quickly usually sucks the water along with it, which acts like a suction cup, but doing so slowly has no such limitation as air can freely flow under it.
> where it takes a crane to remove a mattress from a pool
Mattresses are made of fluffy materials, often held apart by things like springs. A relatively small portion of their volume is actually solid material, the rest being composed of air.
If a mattress is dropped into a lake then it will soak up water, displacing the air inside the mattress with the much heavier and more dense water. Then when you try to pull it out you are actually trying to lift up much more weight than with a dry mattress.
You can try this for yourself in a tub or shower with a towel. First feel how heavy the towel feels when dry, then wet it thoroughly under the water. Now feel how much heavier it is. Then you can wring out the towel and see some of the water be pushed out which you were also lifting.
think of the mattress as a gigantic bucket, which weighs nothing in the water, but once it hits the surface weights a tonne. hence the videos of cranes flipping over when attempting to extract cars from the water.
I don’t really understand your questions but if your asking why a mattress filled with 100 gallons of water is heavier than a floatie filled with weightless air it’s because water is heavy and air is not heavy. If your asking why things are less heavy underwater it’s because gravity and buoyancy make things seem weightless under water
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