# centerOfMassOffset The position of the body’s center of mass relative to its local coordinate origin. ``` var centerOfMassOffset: SCNVector3 { get set } ``` ## Discussion The results of physics interactions with a body depend on its center of mass. For example, a collision close to or in line with the center of mass tends to move the whole body (that is, it adds linear velocity), but a collision not aligned with the center of mass tends to cause the body to rotate or topple (that is, it adds angular velocity). When this property’s value is the vector `(0, 0, 0)` (the default), SceneKit simulates interactions with the assumption that the body’s center of mass is at the origin of its local coordinate space (the [`simdPosition`](/documentation/SceneKit/SCNNode/simdPosition) of the node owning the physics body). Change this value when you want to introduce a difference between the object’s geometric center and its center of mass. For example: - To simulate a body with uneven distribution of mass, such as a hammer with a long handle and heavy head. - To use a point other than the center of mass for positioning the object in the scene, such as the point where the object rests on a surface. --- 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)