🔍 Key Concepts

• Use Archimedes’ principle: the barge’s total weight when loaded equals the weight of the water displaced at 5 ft draft • Compute displacement in salt water using: Volume (ft³) × 64 lb/ft³, then convert pounds to long tons (2240 lb) • Remember to subtract the lightship weight (22.9 long tons) from the total loaded displacement to get cargo weight

💭 Think About

• Based on the 40’ × 20’ dimensions and a 5 ft draft, what is the underwater volume of the barge if you treat it as a simple rectangular box, as suggested by the illustration? • Once you find the total displacement in long tons at 5 ft draft, how does that compare to the barge’s empty weight, and what does the difference represent? • Which of the choices is closest to the cargo weight you get after converting from pounds to long tons and rounding reasonably?

✅ Before You Answer

• Carefully multiply L × W × draft in feet to get the underwater volume in cubic feet • Use 64 lb/ft³ for salt water density and 2240 lb/long ton in your conversions • Be sure to subtract the 22.9 long tons lightship weight at the end, not at the beginning