diff --git a/src/casus.py b/src/casus.py
index bbbf53e..30e70bb 100644
--- a/src/casus.py
+++ b/src/casus.py
@@ -26,12 +26,15 @@ s_list = []
 t_list = []
 
 for i in range(round(10/dt)):
-    if(v==0)
-    F_eff = F_eff+(F_aan-F_rol)
+    if(v_kar < 0):
+        F_rol=0
+        F_eff=0
+
     a_kar = F_eff/(m/4)
     v_kar = v_kar+a_kar*dt
     s_kar = s_kar+v_kar*dt
-    
+    F_eff = (F_aan-F_rol)
+
     F_list.append(F_eff)
     v_list.append(v_kar)
     s_list.append(s_kar)