Contest question! The sinking oil barge. Help!! OK. Here it goes! A tugboat is towing an oil barge in the sea. You may consider the barge to be a large steel container, with an empty weight of 3000 tons, completely filled with 50000 tons of oil. The density of steel is six times that of sea water, and the density of oil is three-quarters that of sea water. An industrial saboteur from certain pipe-line interests opens some drain and vent valves. This lets oil leak out at a constant rate of one ton per second, and water flows in to keep the barge full. How long will the resulting oil slick be if a speed of ten kilometres per hour is maintained until the barge sinks?(Answers in km) I know the density of the barge must be equal to the density of water when it submerges. I also know that the weight of the barge when it sinks is equal to the oil left inside the barge and the water in. This question is something related to specific gravity which is new to me and I'm having problems with.