My dad has a tub by a lake. He has a water pump in the lake to pump up water into a tub.
He claims that if he use a flexible hose, the pressure in the hose at the top will be lower than if he use a rigid hose. The pump has to keep a flexible hose stretched, causing a pressure drop, he says.
I say that if the diameter of the hose doesn’t change while the pump runs, there will be no pressure drop, so once the pump is fully running, it doesn’t matter if the hose is flexible or not.
Who is right?