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A container holds oil of density 0.8 g/cc resting on top of mercury of density 13.6 g/cc. A solid sphere floats so that exactly half of its volume is submerged in mercury and the remaining half is in the oil. Find the density (in g/cc) of the sphere's material.
- 14.4
- 7.2
- 3.6
- 12.2
Correct answer: 7.2
Solution
Buoyancy from oil (half volume) plus buoyancy from mercury (half volume) equals the sphere's weight. This gives the sphere density as the average of the two liquid densities since equal volumes are submerged in each.
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