What is the purpose of Mass in Physics Properties for Active Rigid Body?
If you have three cubes (1 kg, 10 kg, 100 kg), everything else the same and let them fall onto a Passive object, they behave exactly the same (they bounce the same height, etc.).
Is Mass in Blender just for collisions?
Things fall at same speed in vacuum because there is no air resistance - same thing in Blender (and any/most other 3d program).
So yeah, it’s for collisions, unless you add forces such as wind.
Yes, I expected the three objects with different mass to fall at the same speed (Galileo, et al) but I expected the cube with the mass of 1 kg to bounce higher than the cube with the mass of 100 kg.
I must admit, I’ve never investigated how mass works, but have wondered about it myself. It’s used in collisions but not always. Maybe the mass is a relative thing then.
For instance, I just tried fracturing 3 cubes. Fractures from cube 1 were set to 0.1kg, From cube 2 to 100kg and from cube 3 to 1000kg - They feel with some gap between each “cube” and I didn’t notice any difference between them regarding how they came apart.
But if I took one fractured object and changed it’s mass, then I’d see a difference.
Would like to see your experiment (if you are happy to share it). Mass seems to make a difference (sometimes) but how or why is unclear. Volume of object makes a big and noticeable difference. Maybe the source code for Blender Physics is available to read?