Question

A hemispherical tank full of water is emptied by a pipe at the rate of $5$ litres per second. How much time will it take to empty half of the tank, if it is $3.5m$ in diameter?

Answer 1

Volume of the hemisphere is given by: $V=\frac{2}{3}\pi R^3$

$V\approx \frac{2}{3}\times \frac{22}{7}\times {\left(\frac{7}{2}\right)}^3$

$V=\frac{539}{6}{m}^3$

$5liters=0.001\times 5m^3=0.005m^3$

Time taken to empty $0.005m^3$ is $1sec$

Time taken to empty $\frac{539}{6}{m}^3$ is $t=0.005\times \frac{539}{6}sec$

$t=\frac{539}{1200}sec$