The Physics Manager lets you provide global settings for 3D physics (menu: Edit > Project Settings > Physics). There is also a corresponding manager for 2D physics, described here.
|Gravity||The amount of gravity applied to all Rigidbodies. Usually gravity acts only on the Y-axis (negative is down). Gravity is world units per second squared. Note: Increasing the gravity might require increasing the “Solver Iteration Count” to maintain stable contacts.|
|Default Material||The default Physics Material that will be used if none has been assigned to an individual Collider.|
|Bounce Threshold||Two colliding objects with a relative velocity below this value will not bounce. This value also reduces jitter so it is not recommended to set it to a very low value.|
|Sleep Threshold||The mass-normalized kinetic energy threshold below which a non-kinematic Rigidbody may go to sleep. Rigidbodies whose kinetic energy divided by their mass is below this threshold will be candidates for sleeping.|
|Default Contact Offset||Specifies distance which the collision detection system uses to generate collision contacts. The value must be positive and if set too close to zero can cause jitter. Default: 0.01. Only Colliders whose distance is less than the sum of their contact offset values will generate collision contacts.|
|Solver Iteration Count||Determines how accurately joints and contacts are resolved. Usually a value of 7 works very well for almost all situations.|
|Queries Hit Triggers||If enabled, any Raycast, SphereCast, SphereTest, etc. that intersects with a Collider marked as a Trigger will return a hit. If disabled, these intersections will not return a hit. Individual raycasts can override this behavior.|
|Enable Adaptive Force||The “adaptive force” affects the way forces are transmitted through a pile or stack of objects with the aim of giving more realistic behaviour. This option enables or disables the adaptive force. Note that from Unity 5.0, this is disabled by default.|
|Layer Collision Matrix||Defines how the layer-based collision detection system will behave.|
The settings of the physics manager define limits on the accuracy of the physical simulation. Generally speaking, a more accurate simulation requires more processing overhead, so these settings offer a way to trade off accuracy against performance. See the Physics section of the manual for further information.