2D Velocity Damping

Follow-up of our discussion on discord:

I'm making a top-down 2d tile game, which requires basic collisions and movement mechanics. When a kinematic/dynamic object collides with another dynamic object, since there is no "ground" per se, the objects will travel indefinitely with constant velocity. Applying friction is a pretty simple matter of looping over all of the colliders in the world, but getting the friction right with respect to the material and mass isn't as easy in a way that isn't fragile.