[Home](./index.md) > [server](./server.md) > [RigidBody](./server.rigidbody.md) > [effectiveWorldInversePrincipalAngularInertiaSqrt](./server.rigidbody.effectiveworldinverseprincipalangularinertiasqrt.md) ## RigidBody.effectiveWorldInversePrincipalAngularInertiaSqrt property The effective world inverse principal angular inertia square root of the rigid body. **Signature:** ```typescript get effectiveWorldInversePrincipalAngularInertiaSqrt(): SpdMatrix3 | undefined; ```