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 .