if by Poiseuille’s Law, the greater the radius/diameter of a tube the faster the flow, why does water flow faster out of a hose when you put your thumb over the nozzle?

Question

if by Poiseuille’s Law, the greater the radius/diameter of a tube the faster the flow, why does water flow faster out of a hose when you put your thumb over the nozzle?

In: 7

Answer 1

there is a difference between flow rate (liters per second) and flow speed (meters per second)

eli5, if you have big buckets you can move lots of water without running, if you have tiny buckets you have to run really fast to keep up