Door closer

                        Automatic Door Closing Mechanism

            College hostel is you know what !!

            We (all of roommates tend to keep the door closed),

            Every 5 minute someone enters or leaves the room, door opens,

           So, the requirement of above title is very clear to you,

          I, with my roommates , Using: two pulleys, some nylon, weight (700 ml waterfilled
          bottle), and A GREAT IDEA, created arrangement as below,,

          Observe position of weight ( bottle tied on left)