Velocity of efflux, v = √2gh where, h = depth of orifice below the free surface of liquid.
Horizontal range, S = √4h( H— h) where, H = height of liquid column.
Horizontal range is maximum, equal to height of the liquid column H, when orifice is at half of the height of liquid column.
Important Points
In a pipe the inner layer. central layer) have maximum velocity and the layer in contact with pipe have least velocity. Velocity profile of liquid flow in a pipe is parabolic.
Solid friction is independent of area of surfaces in contact while viscous force depends on area of liquid layers. A lubricant is chosen according to the nature of machinery. In heavy machines lubricating oils of high viscosity are used and in light machines low viscosity oils are used. The cause of viscosity 1 liquids is the cohesive forces among their molecules while cause of viscosity in gases is diffusion.