A raft is made of 12 logs lashed together. Each is 45 cm in diameter and has a length of 6.5 m. How many people can the raft hold before they start getting their feet wet, assuming the average person has a mass of 68 kg? Do not neglect the weight of the logs. Assume the specific gravity of wood is 0.60.

(II) A crane lifts the 21,000-kg steel hull of a sunken ship out of the water. Determine

(b) the tension when the hull is completely out of the water.

(II) A crane lifts the 21,000-kg steel hull of a sunken ship out of the water. Determine

(a) the tension in the crane’s cable when the hull is fully submerged in the water , and

(III) A 3.75-kg block of wood (SG = 0.50) floats on water. What minimum mass of lead, hung from the wood by a string, will cause the block to sink?

A ship, carrying fresh water to a desert island in the Caribbean, has a horizontal cross-sectional area of 2240 m² at the waterline. When unloaded, the ship rises 8.55 m higher in the sea. How much water (m³) was delivered?

(II) A cube of side length 10.0 cm and made of unknown material floats at the surface between water and oil. The oil has a density of 810 kg/m³ . If the cube floats so that it is 72% in the water and 28% in the oil, what is the mass of the cube and what is the buoyant force on the cube?

(b) To ensure that a ship is in stable equilibrium, would it be better if its center of buoyancy was above, below, or at the same point as its center of gravity? Explain.

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A simple model (Fig. 13–62) considers a continent as a block ( density ≈ 2800 kg/m³) floating in the mantle rock around it ( density ≈ 3300 kg/m³) . Assuming the continent is 35 km thick (the average thickness of the Earth’s continental crust), estimate the height of the continent above the surrounding mantle rock.

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A copper (Cu) weight is placed on top of a 0.40-kg block of wood (density = 0.60 x 10³ kg/m³) floating in water, as shown in Fig. 13–60. What is the mass of the copper if the top of the wood block is exactly at the water’s surface?

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