Greetings, folks!
I’d like to ask what units Roblox uses for the quantities Mass, Density and Gravitational Acceleration.
I need to know for the sake of some calculations I want to tackle.
Any aid is surely appreciated!
Studs are the standard units for measurement.
Distances, Sizes, Positions are all studs.
Volume is in cubic studs.
Velocity is in studs per second.
Density is a scale value. Density can be different per part based on material or custom setting.
Mass = Volume * Density
Gravity Acceleration is in studs per second squared.
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I thought volume was cubic studs. 
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Edited my initial post to fix that. Thanks.
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The real trouble would seem to be Density.
We know that Density’s value varies with materials and settings, but we don’t know its units.
Knowing the units of either Density or Mass can reveal that of the other.
Density is universally defined as dividing the mass by the volume. In Roblox it’s a scale value.
You can use :GetMass() on parts to get their mass without calculating it yourself. I have not heard any cases of developers needing to use the density of a part in Roblox game development. It’s usually mass or volume that are needed.
No no, that’s not the matter. The matter is the units of Density and Mass.
When I hit :GetMass(), I don’t know the units of mass in question - is it a kilogram? Is it a slug? Or is it some custom unit?
I can get the magnitudes of the mass and density, but I can’t seem to make sense of them without their units. It makes the calculations weirder.
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We don’t have a name for the virtual units of mass.
It’s relational to Volume, which is studs^3.
I just call it mass, I guess. haha
If you want it to be relative to some kind of measurement that you know, you’d have to decide on what the scale of your game is, like what a stud is equivalent to, and work things out from there.
Based on the default setting for gravity I would imagine it’s some custom unit. Although I’m not totally sure on that.