# Question Angular Drag vs. Inertia

Discussion in 'Physics' started by matthrubii, Jul 26, 2020.

1. ### matthrubii

Joined:
Mar 19, 2020
Posts:
1
Hi,

I'm using Unity 3D to visualize a physical system. To be more specific, a ball balancing on a wheel. As you can imagine the masses and the geometry (radii of the wheel and the ball) play a huge role, and therefore does the inertia (here i'm referring to the inertia with respect to the center of the wheel, assuming also that this is the center of mass of the to objects). I also made sure that the sizes in the coordinate system, the mass, the gravity and the friction (no sliding) where right.

I found that by leaving the angular drag (AD) at 0, the system behaved kind of well at the beginning but it was like the ball and the wheel don't had any inertia. As I increased the AD, the system behaved a lot more realistic. I read that the angular drag in Unity adjusts "how hard it is to rotate something", therefore the inertia must be some kind of equivalent, am I right? If yes, then how is the angular drag scaled, because if I would type in the inertia in SI units, the result was not satisfying at all. And if it is not equivalent, is there a way to define the inertia of objects? (I mean the total mass and the geometry are defined, so it is only a question of the distribution of mass inside the object...)