
= Weight of displaced oil + Weight of displaced water
==> $mg = {V_1}{\rho _0}g + {V_2}{\rho _W}g$
==> $m = (10 \times 10 \times 6) \times 0.6 + (10 \times 10 \times 4) \times 1$ $= 760\, gm.$
$(A)$ $\frac{\left|\overrightarrow{ V }_{ P }\right|}{\left|\overrightarrow{ V }_{ Q }\right|}=\frac{\eta_1}{\eta_2}$ $(B)$ $\frac{\left|\overrightarrow{ V }_{ P }\right|}{\left|\overrightarrow{ V }_{ Q }\right|}=\frac{\eta_2}{\eta_1}$
$(C)$ $\overrightarrow{ V }_{ P } \cdot \overrightarrow{ V }_{ Q } > 0$ $(D)$ $\overrightarrow{ V }_{ P } \cdot \overrightarrow{ V }_{ Q } < 0$