$(7.)$ Two cylinders are filled with liquid water, $=1000k\frac{g}{m^3},$ and connected by a line with a

closed valve, as shown in the figure. A has $100$ kg and $B$ has $500$ kg of water, their cross$-$

sectional areas are $A_A=0\mathrm{.}1m^2$ and $A_B=0\mathrm{.}25m^2,$ and the height $h$ is $1$ m $.$ Find the

pressure on either side of the valve. The valve is opened and water flows to an

equilibrium. Find the final pressure at the valve location. $($Ans$.125\mathrm{.}2$kPa $)$

Problem $7$