diff --git a/class_materials/exercises/particle_update_position.ipynb b/class_materials/exercises/particle_update_position.ipynb
index b3d829a..0a2772c 100644
--- a/class_materials/exercises/particle_update_position.ipynb
+++ b/class_materials/exercises/particle_update_position.ipynb
@@ -17,7 +17,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 1,
+   "execution_count": 10,
    "metadata": {
     "ExecuteTime": {
      "end_time": "2018-07-27T15:05:51.531289Z",
@@ -35,7 +35,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 2,
+   "execution_count": 11,
    "metadata": {
     "pycharm": {
      "name": "#%%\n"
@@ -52,20 +52,25 @@
    ],
    "source": [
     "class Particle:\n",
-    "    def __init__(self, mass, velocity):\n",
+    "    def __init__(self, mass, velocity, position):\n",
     "        self.mass = mass\n",
     "        self.velocity = velocity\n",
+    "        self.position = position\n",
     "\n",
     "    def momentum(self):\n",
     "        return self.mass * self.velocity\n",
     "\n",
-    "particle = Particle(mass=2.1, velocity=0.8)\n",
+    "    def update_position(self, dt):\n",
+    "        self.position = self.position + self.velocity * dt\n",
+    "        return self.position\n",
+    "\n",
+    "particle = Particle(mass=2.1, velocity=0.8, position=8.2)\n",
     "print(particle.momentum())"
    ]
   },
   {
    "cell_type": "code",
-   "execution_count": 3,
+   "execution_count": 12,
    "metadata": {},
    "outputs": [
     {
@@ -84,10 +89,24 @@
   },
   {
    "cell_type": "code",
-   "execution_count": null,
+   "execution_count": 13,
    "metadata": {},
-   "outputs": [],
-   "source": []
+   "outputs": [
+    {
+     "data": {
+      "text/plain": [
+       "8.28"
+      ]
+     },
+     "execution_count": 13,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "dt=0.1\n",
+    "particle.update_position(dt)"
+   ]
   },
   {
    "cell_type": "code",
@@ -104,7 +123,7 @@
  "metadata": {
   "hide_input": false,
   "kernelspec": {
-   "display_name": "Python 3 (ipykernel)",
+   "display_name": "Python 3",
    "language": "python",
    "name": "python3"
   },
@@ -118,7 +137,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.10.11"
+   "version": "3.13.7"
   },
   "toc": {
    "nav_menu": {