Physics

Problem

A uniform metal rod

40\,\text{cm}

long floats vertically in a beaker so that its bottom

10\,\text{cm}

is in mercury of density

13.6\,\text{g cm}^{-3}

, the next

20\,\text{cm}

is in water of density

1.0\,\text{g cm}^{-3}

and the top

10\,\text{cm}

is above the water surface. Neglecting the buoyant effect of air, what is the density of the metal? a)

3.4\,\text{g cm}^{-3}

5.2\,\text{g cm}^{-3}

7.0\,\text{g cm}^{-3}

3.9\,\text{g cm}^{-3}