A tank is filled with water of density 103 kg/m3 and oil of density 0.9 x 103 kg/m3. The height of water layer is 1 m and that of the oil layer is 4 m. The velocity of efflux froman opening in the bottom of the tank is

Let dw and do be the densities of water and oil, respectively. Then the pressure at the bottom of the tank is hwdwg+h0d0g. Let this pressure be equivalent to pressure due to water of height h. Then,hdwg=hwdwg+h0d0g∴ h=hw+h0d0dw=1+4×0.91=4.6m According to Torricelli's theorem,v=2gh=2×10×4.6m/s=92m/s