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

# mass

The mass of the body, in kilograms.

## Declaration

```swift
var mass: CGFloat { get set }
```

## Discussion

Discussion The mass of a body affects its momentum and how it responds to forces. The default mass for dynamic bodies is 1.0. The default mass for static and kinematic bodies is 0.0, but these bodies are unaffected by mass. Note that you need not use realistic measurements for the bodies in your app—the effects of the physics simulation depend on the relative masses of different bodies, not the absolute values. You may use whatever values produce the behavior or gameplay you’re looking for as long as you use them consistently.

## See Also

### Defining a Body’s Physical Properties

- [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)
- [usesDefaultMomentOfInertia](scenekit/scnphysicsbody/usesdefaultmomentofinertia.md)
- [centerOfMassOffset](scenekit/scnphysicsbody/centerofmassoffset.md)