diff --git a/lib/objects.py b/lib/objects.py
index 893f3b8..3c92dee 100755
--- a/lib/objects.py
+++ b/lib/objects.py
@@ -157,5 +157,8 @@ class System:
         self.update_jp()
         self.update(dt)
         self.time = self.time + dt
+        for body in self.bodylist:
+            body.p = body.v*body.m
+
+        return 1
 
-        return 1
\ No newline at end of file