---
title: massProperties
framework: realitykit
role: symbol
role_heading: Instance Property
path: realitykit/physicsbodycomponent/massproperties
---

# massProperties

The physics body’s mass properties, like inertia and center of mass.

## Declaration

```swift
var massProperties: PhysicsMassProperties
```

## Discussion

Discussion By default, the mass properties value is default, which matches the properties of a unit sphere with mass of 1 kilogram.