Problem $2$: The two reservoirs are connected with a cast iron pipe. The total length of the pipe is $20$ m $.$ For the first $15$ m $,$ from high level tank, the diameter is $150$ mm and then diameter is suddenly enlarged to $300$ mm $.$ Calculate the flow rate of water if the level of tank $1$ is $18$ m higher than tank $2.$ Consider all losses and take value of coefficient of friction $f$ as $0\mathrm{.}02$ for all sections of pipe.

Ans: $Q=0\mathrm{.}115\frac{m^3}{(s)}$