Angle of repose is defined as steepest angle of descent or dip. It is with relation to horizontal plane to which a material can be piled. The minimum value for angle of repose is zero degrees. It lies on horizontal surface. Therefore, re is no sliding.

Fluid flow is laminar as it is assumed to be incompressible and Newtonian. The flow is laminar through pipe of constant cross section. Thus, re is no acceleration of fluid in pipe. Therefore, Hagen-Poiseuille assumed that fluid flow is laminar.

Hydraulic diameter handles flow in non-circular channels and tubes. The most suitable term to calculate hydraulic diameter for a round tube is D_h= 4A/P. Where ?A? is cross-sectional area and ?P? is wetted perimeter.

Coefficient of viscosity is defined as degree to which fluid resists flow under an applied force. It is expressed as a ratio of shearing stress to velocity gradient. It has a unit of Nsm^-2.

Moody chart is a graph of frictional factor(f) vs Reynolds numbers. It gives various values corresponding to ?k/d? ratios. Where ?k? is measure of wall roughness and ?d? is pipe diameter.

Fluid sealing in a dashpot is achieved using a piston ring. Piston rings are a number of narrow iron rings which are fitted loosely into grooves of piston. The rings split at a point on rim which is placed just below crown.

Shape is one of most important factors for a fluid. The forces or than gravity that fall on fluid affects outcome. Thus, changing shape of fluid cannot be controlled.

Relative roughness is defined as quantity used to measure roughness of pipe?s surface. It is equal to average height of surface irregularities divided by pipe diameter. Therefore, Relative roughness= ?/D.

Shear stress is defined as force acting per unit area. Thus, unit of shear stress is equal to N/m². Since, 1 Pa =1 N/m², Pascal is most suitable one.

If Reynolds number of flow is below its lower critical Reynolds number, flow is clearly laminar. The maximum diameter can be found for Re = 2100. The diameter comes out to be 2.1 mm.