The reading of pressure meter attached with closed water pipe is $3.5 imes 10^{5}$ newton/metre ${

Question

The reading of pressure meter attached with closed water pipe is $3.5 	imes 10^{5}$ newton/metre ${ }^{2}$. On opening the valve of the pipe the reading of the pressure meter reduces to $3.0 	imes 10^{5}$ newtons $/$ metre $^{2}$. The speed of water flowing in the pipe is\

Professor PC Thomas Classes · Answer

By Bernoullis theorem Pr. $\mathrm{E}+\mathrm{KE}$ before opening the tap $=\operatorname{Pr} . \mathrm{E}+\mathrm{KE}$ after opening the tap.\ $\frac{P_{1}}{ho}+\frac{1}{2} v_{1}^{2}=\frac{P_{2}}{ho}+\frac{1}{2} v_{2}^{2}$\ $v_{1}=0$ when the tap is closed\ $	herefore \frac{1}{2} v_{2}^{2}=\frac{\mathrm{P}_{1}-\mathrm{P}_{2}}{ho} \quad v_{2}=\sqrt{\frac{2\left(\mathrm{P}_{1}-\mathrm{P}_{2}ight)}{ho}}$\ $\mathrm{P}_{1}=3.5 	imes 10^{5} \mathrm{~N} / \mathrm{m}^{2} \quad \mathrm{P}_{2}=3 	imes 10^{5} \mathrm{~N} / \mathrm{m}^{2}$\ $ho=1000 \mathrm{~kg} / \mathrm{m}^{3} \quad$ Calculate $v_{2}$\