---
title: speed
framework: spritekit
role: symbol
role_heading: Instance Property
path: spritekit/skphysicsworld/speed
---

# speed

The rate at which the simulation executes.

## Declaration

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

## Discussion

Discussion The default value is 1.0, which means the simulation runs at normal speed. A value other than the default changes the rate at which time passes in the physics simulation. For example, a speed value of 2.0 indicates that time in the physics simulation passes twice as fast as the scene’s simulation time. A value of 0.0 pauses the physics simulation.

## See Also

### Configuring the Physics World

- [gravity](spritekit/skphysicsworld/gravity.md)