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A solid hemisphere is just pressed below the surface of a liquid (flat face upward, curved surface downward). Find the ratio F1/F2, where F1 is the net hydrostatic force on the curved surface and F2 is the net hydrostatic force on the flat face. Neglect atmospheric pressure.
- 1/2
- 2/3
- 1/3
- none of these
Correct answer: 1/3
Solution
With the flat face at the top (depth R) and the curved dome just below the surface (top of dome at depth 0), the force on the flat face F2 = rho*g*R*pi*R² and the net downward force on the curved surface F1 = rho*g*pi*R³/3, giving F1/F2 = 1/3.
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