The unit given in the “length” field is a mysterious “N.m” , what does this mean? How to properly use this unit?
From what I remember from physics class N m is Newton (a unit for force) per meter (unit for distance)
Okay, thanks, that’s less mysterious but still not super helpful.
Meters are defined by the scene physics scale in scene properties.
I’m gonna be hopeful and suppose that the density behavior parameter is in kilograms per square meter, but I’m not so sure it’s noted anywhere.
Let’s assume a 1x1 object with a square physics2 hitbox, a density of 1, a linear damping of 0, which isn’t experiencing any gravity or friction effects.
This is pretty much an object in the void of outer space.
If any force is applied to it (an impulse is an instantaneous application of force), this object will reach a certain velocity and just keep at it forever (let’s forget about rotation)
If an impulse of 1 N.m is applied to such an object, what velocity would it reach? One meter per second?
Yes, I assume it would be 1m/s.
Then it depends on the point of application of the force and the world scale you choose.
Why don’t you set up a sandbox? 
Hey, thanks for replying.
That’s exactly what I was thinking of doing, because probably I won’t 100% grasp it unless I make such a thing.