A liquid of density is coming out of a hose pipe of radius a with...

Mass per unit time of the liquid = \rhoav Momentum per second carried by liquid $=\rho a v \times v$ Net force due to bounced back liquid, $\mathrm{F}_{1}=2 \times$\left[\frac{1}{4} \rho \mathrm{av}^{2}\right]$Net force due to stopped liquid,$\mathrm{F}_{2}=\frac{1}{4}$pav$^{2}$Total force,$\mathrm{F}=\mathrm{F}_{1}+\mathrm{F}_{2}=\frac{1}{2} \rho \mathrm{av}^{2}+\frac{1}{4} \mathrm{pav}^{2}=\frac{3}{4} \mathrm{pav}^{2}$Net pressure$=\frac{3}{4} \rho v^{2}