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Raft made of logs
A raft is fashioned by lashing 8 loges together side by side. Each log is 2 m long, has a diameter of 60 cm, and a mass of 300 kg. How much weight can the raft carry. If duct tape were used to make the rafter water-tight between the logs (so that the raft is approximated a rectangular prism with a pair of rounded sides), how would this weight change?
Customer support service by UserEcho
For the first question, you can simply think of the problem as a balance of forces. You need to balance them by equating the buoyant force and the force of gravity of some arbitrary mass (call it M). After solving for M, just subtract off the mass of the raft to give you the total mass you can add without the raft sinking.
For the second question, are you asking how the weight change if you evaluated the problem as a perfect rectangular box instead of a box with rounded edges? If so, then it would change how strong the buoyant force is because the volume of the raft would be different.
V = L*D^2*8 vs V = L*D*7 + pi*(D/2)^2, where
L = length of logs
D = diameter of logs