1678 A barge of mass 15,000 kg, made from metal of density 7500 kg/m², is being loaded in a closed canal lock of surface area 6633 m² with ore of density 3 gm/cm'. When 80,000 kg of ore are put aboard, the barge sinks. How much does the water level in the lock change? Does it rise or fall? The area of the barge can be assumed negligible in comparison with the area of the lock. NOTE: You are to find the difference in the level of the water in the dock between the level when the barge is full, ready to sink, and the level when the barge has sunk and is resting on the bottom of the lock.