diff -r 44b49f255e31 -r d5e6c8c92d87 rust/hwphysics/src/lib.rs
--- a/rust/hwphysics/src/lib.rs	Thu Jan 27 03:51:13 2022 +0300
+++ b/rust/hwphysics/src/lib.rs	Fri Jan 28 02:33:44 2022 +0300
@@ -6,7 +6,10 @@
 
 use integral_geometry::PotSize;
 use land2d::Land2D;
+use std::any::{Any, TypeId};
 
+use crate::collision::CollisionData;
+use crate::physics::VelocityData;
 use crate::{
     collision::CollisionProcessor,
     common::{GearAllocator, GearId, Millis},
@@ -52,9 +55,20 @@
         let collisions = self.collision.process(land, &updates);
     }
 
-    #[inline]
     pub fn add_gear_data<T: Clone + 'static>(&mut self, gear_id: GearId, data: &T) {
         self.data.add(gear_id, data);
+        if TypeId::of::<T>() == TypeId::of::<VelocityData>() {
+            self.collision.remove(gear_id);
+        }
+    }
+
+    pub fn remove_gear_data<T: Clone + 'static>(&mut self, gear_id: GearId) {
+        self.data.remove::<T>(gear_id);
+        if TypeId::of::<T>() == TypeId::of::<VelocityData>() {
+            if let Some(collision_data) = self.data.get::<CollisionData>(gear_id) {
+                self.collision.add(gear_id, *collision_data);
+            }
+        }
     }
 
     #[inline]
@@ -72,12 +86,12 @@
         World,
     };
     use fpnum::{fp, FPNum, FPPoint};
-    use integral_geometry::PotSize;
+    use integral_geometry::{PotSize, Size};
     use land2d::Land2D;
 
     #[test]
     fn data_flow() {
-        let world_size = PotSize::new(2048, 2048).unwrap;
+        let world_size = PotSize::new(2048, 2048).unwrap();
 
         let mut world = World::new(world_size);
         let gear_id = world.new_gear().unwrap();
@@ -95,7 +109,10 @@
             },
         );
 
-        let land = Land2D::new(Size::new(world_size.width - 2, world_size.height - 2), 0);
+        let land = Land2D::new(
+            Size::new(world_size.width() - 2, world_size.height() - 2),
+            0,
+        );
 
         world.step(Millis::new(1), &land);
     }