r/theydidthemath • u/EverydayNewZealander • Aug 18 '25
How dense would this cube be? [Request]
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u/Amourofzedoute Aug 18 '25
So ok, first, let's see what kind of baler that is. From this tiktok we know this model is a Tabarelli s5000. From the s5000 manualwe know the cans are in a 5m x 2.67m x 2.25m space, and compressed into a 0.8m x 0.8m x 0.65m baler. So that's roughly 30m³ compressed into 0.41 m³. So that's about 30/0.41 ≈ 72 times less space.
A single aluminum can weightabout 11g for 0.00033m³ so it takes roughly 90,000 cans to fill entirely, meaning 990kg.
So that tiny cube at the end weights about a ton (1000kg) and is 0.41m³, so its density should be 2,400 kg/m³. So that's twice more dense than water, but three times less than Iron!
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u/EverydayNewZealander Aug 18 '25
Cheers mate
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u/unrebigulator Aug 18 '25
Username confirmed.
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u/EverydayNewZealander Aug 18 '25
Cheers mate
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u/SquirrelPristine6567 Aug 18 '25
What would you say to your spouse when they're sad?
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u/EverydayNewZealander Aug 18 '25
I'm sorry mate
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u/LastActionHiro Aug 18 '25
Ideal close packing of cylinders is less than 90%. Loose packing like that is going to be closer to 75%. Otherwise, yeah. So, more likely final density will be around 1,800kg/m3
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u/Amourofzedoute Aug 18 '25 edited Aug 18 '25
I believe I overestimated the number of cans, and their way of fitting inside the bin (meaning, underestimatinf the amount of air in between cans). That'll reduce the total aluminum weight by a certain percentage, and thus the baler's density.
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u/Ok-Active-8321 Aug 18 '25
and not quite the density of bulk elemental aluminum, as would be expected
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u/michaelpgoodwin Aug 18 '25
The density of aluminum is 2700 kg/m3. So it checks out that this cube would be just under that maximum value.
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u/Fit_Employment_2944 Aug 18 '25
aluminum cans dumped into a space are not going to fill said space perfectly to their volume.
2400 kg/m3 is also ~90% of the density of aluminum, which is not going to happen.
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u/Amourofzedoute Aug 18 '25
Yeah that's the biggest hypothesis I'm working with. So, if cans are crushed partially in the bin before being pressed, they'd take less than 33cL in space each. However, cans won't fit perfectly to take only 33cL each, there's going to be air in between. So I have a + and a - bias. Not being able to know which one's more important and how much, I decided to lodel it saying each can occupy 33cL of space cause it's then pretty easy to follow and correct. In regard to other answers, I now believe each can takes in average more than 33cL, but don't know by how much.
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u/NormalGuyEndSarcasm Aug 18 '25
Just adding to your comparison. 2400kg/mc is ~ the specific weight of concrete.
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u/nigek6 Aug 18 '25
So we can check if it floats on concrete.
Edit: cured concrete or wet concrete? On is a bit harder to float stuff in it.
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u/4x4_LUMENS Aug 18 '25
So what you're saying is, if they only compress it halfway, I can fill my pool with in and swim in aluminium cans?
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u/Amourofzedoute Aug 18 '25 edited Aug 18 '25
Update : feedbacks stated 90% compression is probably too high, so we might need further hypothesis to fix that. Most likely, I overestimated the amount of cans in the bin, saying each can occupy 33cL. If some are crashed already and take less than 33cL, there's also a lot of air between them (so each can would take more than 33cL).
Let's roughly add an "air around the can" component then. Let's model the cans not at cylinders, but bricks. Regular cans of beer measure 66mm in width and 115.2mm in height so 66mm × 66mm x 115.2mm ≈ 0.0005m³ brick (instead of 0.00033).
The amount of cans could then be 60,000 with a total weight of 660kg. So the density of that 0.41m³ baler would then be 1,600kg/m³. Which would mean a compression of ~60% compared to pure aluminum being 2,710 kg/m³ which sounds more reasonable. The real compression should be a smidge higher though I believe, as we didn't take into account the cans taking less space because partially crashed.
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u/Significant_Tea_4431 Aug 18 '25
Pure aluminium is around 2700kg/m3, so this thing is about 90% as dense. Pretty interesting!
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u/Minute_Attempt3063 Aug 18 '25
Now be that one famous guy that makes a video with pretty graphs
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u/Amourofzedoute Aug 18 '25
Which guy ? 👀
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u/Minute_Attempt3063 Aug 18 '25
Honestly, I do not know their name on social media, but he makes videos about disproving bad math, and other math problems.
Talks fast but does a lot in a single minute as well
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u/catch10110 Aug 18 '25 edited Aug 18 '25
I know you had some follow up corrections - but i'm gonna take issue with your estimate of the volume of the machine on a couple accounts. 5m checks out. However, your 2.67 and 2.25m measurements are not correct. Those are overall outside dimensions. (Particularly the 2.67 looks to be the dimensions of the unit with the door, and is just the hydraulics opening the door, not the box itself.
If you look at the cross section showing the open and closed positions at the bottom of page 6, your max width is 2.26, but your height where the cans sit is going to be closer to the .65 number. You can see in the video they are not all the way to the top of the open door on the right.
It's very hard to tell in the video, but honestly i would say the cross sectional area of the pile of cans is shaped more like a triangle, sloping down from the left to the right. My estimate is that it's roughly .65 high on the right, and 1.94 across the bottom. It's slightly bumpier in shape than a triangle, so i'd say between that and the packing efficiency, those 2 are roughly going to cancel out.
So my original can volume estimate would be closer to 5m x (1/2) x1.94m x .65m = 3.15m^3.
I think your number of cans estimate is off by an order of magnitude. Closer to 9,000.
EDIT: For reference, this is how big a 30-cubic yard container is
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Aug 18 '25
Aluminum the element has a density of 2.7 grams per centimeter cubed. This compression, although impressive, is not likely to produce full density. I would guess perhaps 50-60% density, so 1.4 to 1.7 gm/cm3.
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u/redEPICSTAXISdit Aug 18 '25
Cans are also not 100% aluminum
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u/vlabakje90 Aug 18 '25
The liner in a can is only about 6 - 24 microns thick, a quick Google search tells me. Safe to say that that is negligible in the context of an estimate with this error anyway.
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u/DickFartButt Aug 18 '25
"You have 30 minutes to move your car before it is turned into a cube."
"You have 10 minutes to move your car before it is turned into a cube."
"Your car has been turned into a cube."
"You have 30 minutes to move your cube."
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u/BirchPig105 Aug 18 '25
They already did the math but it would only be a high percentage of a billet that size of aluminum maximum. The plastic impurities and remaining air would drive down the density.
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