Explanation:The three main forces that stop moving objects are friction, gravity and wind resistance. Equal forces acting in opposite directions are called balanced forces. Balanced forces acting on an object will not change the object's motion. When you add equal forces in opposite direction, the net force is zero.
Since no external force is acting except frictional force, so stopping force is frictional force with magnitude ~ 3N in the direction opposite to the motion of sledge.
