141

mass (mander.xyz)

submitted 6 days ago by fossilesque@mander.xyz to c/science_memes@mander.xyz

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[-] niktemadur@lemmy.world 1 points 2 days ago

Curse you, Noneuclid!

[-] untorquer@lemmy.world 3 points 2 days ago

Are we simply to assume the donuts have a homogenous internal structure? Clearly there's not enough information.

[-] KoboldCoterie@pawb.social 150 points 6 days ago

Obviously the left one.

In physics, the center of mass of a distribution of mass in space is the unique point at any given time where the weighted relative position of the distributed mass sums to zero. For a rigid body containing its center of mass, this is the point to which a force may be applied to cause a linear acceleration without an angular acceleration.

If they wanted this to be an actual, debatable question, they shouldn't have used 'center of mass', as the term has a specific definition and the question has a correct answer; it's not open to interpretation, like "How would a horse wear pants?" or similar questions.

[-] fossilesque@mander.xyz 31 points 6 days ago

I don't think it was meant to be taken seriously, but these are the types of comments I was hoping for. ;)

[-] KoboldCoterie@pawb.social 15 points 5 days ago

The most fun thing about this community is responding with serious answers to memes that were intended to be jokes. :)

[-] Bell@lemmy.world 20 points 6 days ago

Wait is this an African horse or a European one?

[-] Thorry84@feddit.nl 16 points 5 days ago

Fully laden or unladen?

[-] Redfox8@mander.xyz 1 points 3 days ago

How would it carry the load?

[-] Trollception@sh.itjust.works 1 points 2 days ago

What gift did it receive for its 3rd birthday?

[-] DonGirses@lemmy.world 14 points 5 days ago

I don't know...

AAAAH

[-] olafurp@lemmy.world 7 points 5 days ago

Choosing the other one would be known as "rimming"

[-] Tolookah@discuss.tchncs.de 11 points 6 days ago

What you don't know is that the mass distribution is extremely uneven as there's a lead ball in the back half (for sweetness), and yeasty air bubbles in the front half.

[-] Contramuffin@lemmy.world 2 points 6 days ago

If a donut were to have a center of mass, would the center of mass be like this or like this?

[-] bleistift2@sopuli.xyz 2 points 6 days ago

Would you mind sharing the source of that quote? I’m curious about the ‘relative position […] sums to zero’—relative to what? Suppose the mass is completely contained in the ‘upper right quadrant’ in 3D space (I’m lacking the language skill to express that accurately). Then I can’t find a definition that wouldn’t cause the sum to be positive.

[-] KoboldCoterie@pawb.social 7 points 6 days ago* (last edited 6 days ago)

I just grabbed it from Wikipedia, so it's likely written to be understandable to a layman (which is good, because that's what I am).

That said, it's just referring to the mass relative to the point you're declaring the center of mass. If there's 15g on the left, there should be 15g on the right; think of it like the center of mass being (0,0,0) on a 3 dimensional graph. 15g on one side is "negative" and on the other is "positive", so the sum at the (0,0,0) point is 0g.

[-] DannyBoy@sh.itjust.works 56 points 5 days ago* (last edited 5 days ago)

In high school we were taught if the center of mass wasn't on any mass then the center of mass was "virtual". But yes the center of mass doesn't have to exist on the object.

[-] Kongar@lemmy.dbzer0.com 45 points 5 days ago

Not saying you’re wrong - you’re probably right. But as an engineer, I’ve referred to or been asked about “the center of mass” thousands of times and not once have I ever heard “virtual” used. It’s just always the center of mass - wherever that point exists in all of spacetime.

It’s weird. Did something change over the years (like using the Oxford comma or double spacing after a period?). Or is that something that’s always been a thing that I’ve never run across? Strange ;)

[-] DannyBoy@sh.itjust.works 17 points 5 days ago

After doing a search online the only reference to a virtual center of mass is a StackExchange post that says it's from a high school textbook. Must be the same one I had. Seems to be not so common of a term!

[-] kayzeekayzee 11 points 5 days ago* (last edited 5 days ago)

I think the proper term would be "mathematical", bit "virtual" gets the point across just as well in context

[-] DontRedditMyLemmy@lemmy.world 3 points 5 days ago

Spacetime?

[-] kayzeekayzee 48 points 5 days ago

Actually, every donut has a corresponding donut hole somewhere in the world, which holds the center of mass. This property of disconnection between a donut and its CoM has many interesting applications.

[-] Swedneck@discuss.tchncs.de 21 points 5 days ago

sets down donut on table
donut instantly tilts to the side and clips into the table, proceeds to violently vibrate for a second before flying off into space

[-] helpImTrappedOnline@lemmy.world 14 points 5 days ago* (last edited 5 days ago)

Every time you eat a donut hole physics is broken until someone eats a donut.

[-] CaptainBlagbird@lemmy.world 2 points 3 days ago* (last edited 3 days ago)

M'Ass

tips fedora

[-] thann@lemmy.dbzer0.com 16 points 5 days ago

Its a circle in the middle of the bread

[-] BreadOven@lemmy.world 4 points 5 days ago

The secret third option: looking at the picture on the left; going straight through the donut through the middle in the vertical direction.

Although now that I saw it, I still think the original left picture is the correct answer. Even through the middle vertically as I mentioned, the centre of gravity would be the same, would it not?

[-] WolfLink@sh.itjust.works 18 points 5 days ago

Left is correct. The center of mass of a donut is inside the hole, which is “outside the donut”.

This may seem unintuitive, but the center of mass of an object does not have to be inside the object.

This is the mechanism behind these toys:

The wings of the bird and poles of the clown extend below the main body, but are weighted so that’s where most of the weight is. So the center of mass is below the main body, so it will easily balance on the main body. However, your eyes will naturally focus on the main body, which would be unstable without the extra weight hanging off the side, making the balancing look surprising.