System-wide physics settings

You can locate the system-wide physics settings in Settings -> Options -> Physics.

System Physics

Enabled: Turn physics simulation on and off
Gravity: Change gravity force. Set it to negative will reverse the gravity direction.
Disable Collision: Controls collision between model parts. There are 2 types of colliders in a model, type A are the ones that move with animation, like arms and legs, type B are the ones that move freely, usually they are connected to other parts by one or more joints. By default type B will collide with type A but if you turn “Disable Collision” on, then type B objects will no longer collide with type A objects and will penetrate through.
Steps per second: Physics simulation are calculated with a certain interval between steps, and it works best if it is a fixed interval. This option controls how many simulation is performed within a second. The more the better but too many steps will slow down your FPS. It’s best to match it with your FPS for smooth animation.