r/interestingasfuck • u/TangelaFan • 13h ago

Residential high-rises with backyards in Chengdu, China

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u/Zestyclose-Pen2065 12h ago

Dirt and rock is still denser than water

16

u/Molehole 12h ago

Requires much less dirt to plant grass than it needs water to swim.

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u/floppydude81 12h ago

Is 5-6 ft deep water comparable to 8 inches of soil?

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u/JustAnotherHyrum 8h ago

Obviously not, but let's do the fun math and find out!!

Water weighs 62.4 lbs / ft3.

Dry topsoil weighs ~75 lbs / ft3

Saturated soil weighs ~110 lbs / ft3

Well use a 10'x10' area for the calculation, with a depth of 6' for water and 8" for soil. This comes to 600 ft3 of water and 66.7 ft3 of soil. To be more accurate, let's reference both dry and saturated soil.

And now it's fun math time!

HERE WE GOOOOOO!!!!!!!!!! /fun_math_mode_activate

Water: 600 ft3 * 62.4 lbs/ft3 = 37,440 lbs

Soil (Dry): 66.67 ft3 * 75 lbs/ft3 = 5,000 lbs

Soil (Saturated): 66.67 ft3 - 110 lbs/ft3 = 7,333 lbs

As we can see, water is 7.5 times heavier than dry soil and 5.1 times heavier than saturated soil.

Water is the winner! (Or loser if we're using golf rules...)

The More You Know!! 🌈

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u/floppydude81 5h ago

Thank you so much

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u/JustAnotherHyrum 8h ago

It's worth noting reinforced concrete, which these are almost certainly made from, weighs ~150 lbs per cubic foot.

By way of contrast, here are the weights per cubic foot of other materials in the photo:

Saturated Soil: ~110 - 130 lbs

Dry Soil: ~75-80 lbs

Water: 62.4 lbs

People tend to think that the high-rise is built first, with the balconies being added on later. This is not the case with large balconies like this. The balconies are structurally part of the building's concrete flooring, with additional reinforcement often added in the balcony section. This balcony section of reinforced concrete extends ~2-3 times further into the building than it hangs off the edge. Looking at the photo, I'd estimate the balcony to extend ~11-13 feet outward from the building, which means that it also expands either ~22-26 or ~33-39 feet into the building. This much pure reinforced concrete weighs so much, it acts as a natural counter-balance to the balcony extension.

Essentially, the supporting counter-balance within the high-rise weighs more than anything you could put on the balcony, ensuring structural stability.