# addForce(_:relativeTo:) Applies a force to the physics body at its center of mass. ``` @MainActor @preconcurrency func addForce(_ force: SIMD3, relativeTo referenceEntity: Entity?) ``` ## Parameters `force` A force in newtons. `referenceEntity` The reference entity that defines the coordinate space in which `force` is defined. ## Discussion The physics simulator applies the added force until the end of the frame interval. To continue exerting the force after that time, add the force again with another call to the method. Handle the [`SceneEvents.Update`](/documentation/RealityKit/SceneEvents/Update) event to receive an indication of when the frame interval ends. For an app that renders at 60 frames per second (fps), this event occurs about once per 16 milliseconds. --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)