The hydrostatic force acts through

If a₁ and a₂ are the cross-sectional areas of a tank and orifice, h the height of water level in tank above the centre of the orifice, the velocity of approach is given by

For a most economical rectangular channel, the width of the channel must be

Most economical section of a circular channel for maximum velocity, is if,

In a two dimensional flow if the components of the velocity are u = ax ; v = by, the point where no motion occurs, is known as