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# PhysicsMassProperties

Mass properties of a physics body.

```
struct PhysicsMassProperties
```

## Topics

### Using default mass properties

[`default`](/documentation/RealityKit/PhysicsMassProperties/default)

The default mass properties, equivalent to a unit sphere with a mass of
1 kilogram.

### Creating custom mass properties

[`init()`](/documentation/RealityKit/PhysicsMassProperties/init())

Creates a mass properties instance with default settings.

[`init(mass:inertia:centerOfMass:)`](/documentation/RealityKit/PhysicsMassProperties/init(mass:inertia:centerOfMass:))

Creates a mass properties instance with the given settings.

[`init(shape:density:)`](/documentation/RealityKit/PhysicsMassProperties/init(shape:density:))

Creates the mass properties for a solid shape with the specified
density.

[`init(shape:mass:)`](/documentation/RealityKit/PhysicsMassProperties/init(shape:mass:))

Creates the mass properties for a solid shape with the specified mass.

### Getting mass properties

[`mass`](/documentation/RealityKit/PhysicsMassProperties/mass)

The mass in kilograms.

[`inertia`](/documentation/RealityKit/PhysicsMassProperties/inertia)

The inertia in kilograms per square meter.

[`centerOfMass`](/documentation/RealityKit/PhysicsMassProperties/centerOfMass)

The position of the center of mass and the orientation of the principal
axes.

### Comparing mass properties

## Relationships

### Conforms To

[`Equatable`](/documentation/Swift/Equatable)

---

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