The arrangement shown in the figure measures the velocity $$V$$ of a gas of density $$1kg/{m^3}$$ flowing through a pipe. The acceleration due to gravity is $$9.81m/{s^2}.$$ If the manometric fluid is water (density $${1000kg/{m^3}}$$ ) and the velocity $$V$$ is $$20 m/s,$$ the differential head $$h$$ (in $$mm$$) between the two arms of the manometer is ______.

The water jet exiting from a stationary tank through a circular opening of diameter $$300$$ $$mm$$ impinges on a rigid wall as shown in the figure. Neglect all minor losses and assume the water level in the tank to remain constant. The net horizontal force experienced by the wall is ___________ $$kN.$$

Density of water is $$1000\,\,kg/{m^3}.$$

Acceleration due to gravity $$g = 10\,\,m/{s^2}.$$

A Prandtl tube (Pitot-static tube with $$C=1$$) is used to measure the velocity of water. The differential manometer reading is $$10$$ mm of liquid column with a relative density of $$10.$$ Assuming $$g = 9.8\,\,m/{s^2},$$ the velocity of water (in $$m/s$$) is ___________

Water $$\left( {\rho = 1000kg/{m^3}} \right)$$ flows through a venturimeter with inlet diameter $$80$$ $$mm$$ and throat diameter $$40$$ $$mm.$$ The inlet and throat gauge pressures are measured to be $$400$$ $$kPa$$ and $$130$$ $$kPa$$ respectively. Assuming the venturimeter to be horizontal and neglecting friction, the inlet velocity (in $$m/s$$) is ___________.