# Apply physics forces [Back to Use gameplay actions](https://rustic-game-engine.pages.dev/markdown/guides/gameplay-actions.md). `force(object, vector, delta?)` applies force for the interval, `impulse` / `knockback` add velocity, and `launch` sets velocity. The current simulation uses unit mass. `explosion(center, radius, strength, ignore?)` applies radial distance-falloff impulses and skips anchored bodies. Direct force/impulse/launch on an anchored or nonphysical object is an error. Models do not automatically acquire primitive colliders.