---
title: "init(duration:rate:)"
framework: realitykit
role: symbol
role_heading: Initializer
path: "realitykit/timedforcefalloff/init(duration:rate:)"
---

# init(duration:rate:)

Creates a timed force falloff.

## Declaration

```swift
init(duration: TimeInterval, rate: Double = 1.0)
```

## Parameters

- `duration`: The lifetime of the effect in seconds.
- `rate`: Controls how fast or slow falloff occurs.

## Discussion

Discussion When the rate is 0, no falloff occurs. (Rigid bodies outside the bounds are culled.) When the rate is greater than 0 and less than 1.0, falloff occurs slower and is sublinear. When the rate is 1.0, falloff is linear. When the rate is greater than 1, falloff occurs faster and is nonlinear.