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# init(duration:rate:)

Creates a timed force falloff.

```
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

- 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.

---

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