this works much better, still bad though

examples/demo/src/setup.rs

@@ -34,6 +34,7 @@ pub fn setup_scene(
             transform: Transform::from_xyz(0.0, ground_height, 0.0),
             ..default()
         },
+        RigidBody::Fixed,
         Collider::cuboid(ground_size, ground_thickness, ground_size),
     ));
     // cube
@@ -75,4 +76,4 @@ pub fn setup_scene(
         ),
         ..default()
     },));
-}
+}