---
title: usesDefaultMomentOfInertia
framework: scenekit
role: symbol
role_heading: Instance Property
path: scenekit/scnphysicsbody/usesdefaultmomentofinertia
---

# usesDefaultMomentOfInertia

A Boolean value that determines whether SceneKit automatically calculates the body’s moment of inertia or allows setting a custom value.

## Declaration

```swift
var usesDefaultMomentOfInertia: Bool { get set }
```

## Discussion

Discussion A body’s moment of inertia determines how it responds to torques (that is, forces with a rotational component). If this property is true (the default), SceneKit automatically determines the body’s moment of inertia based on its shape and mass. Set this property to false and use the momentOfInertia property to define a custom moment of inertia (for example, to model an object of non-uniform density).

## See Also

### Defining a Body’s Physical Properties

- [mass](scenekit/scnphysicsbody/mass.md)
- [charge](scenekit/scnphysicsbody/charge.md)
- [friction](scenekit/scnphysicsbody/friction.md)
- [rollingFriction](scenekit/scnphysicsbody/rollingfriction.md)
- [restitution](scenekit/scnphysicsbody/restitution.md)
- [damping](scenekit/scnphysicsbody/damping.md)
- [angularDamping](scenekit/scnphysicsbody/angulardamping.md)
- [momentOfInertia](scenekit/scnphysicsbody/momentofinertia.md)
- [centerOfMassOffset](scenekit/scnphysicsbody/centerofmassoffset.md)