Question

could someone clearly explain to me about Poiseuille's Law of fluid flow through a pipe?

Answer 1

Flow of a fluid through a pipe
Poiseuille's Law

In trying to find out what factors control how fast fluids can flow
through pipes, the following factors are easy to isolate:

The pressure difference between the ends of the pipe. The bigger
the pressure difference, the faster will be the flow.

The length of the pipe. More liquid will flow through a shorter than a
longer pipe in the same time.

The radius of the pipe. More liquid will flow through a wide than a
narrow pipe in the same time. This dependence is very marked.

The coefficient of viscosity of the liquid. Water flows much more
easily than glycerine.

Q = dV/dt = (∆p π R^4)/8ηL