Velocity in Hoses: Why is it Low and What Does it Mean?

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Homework Help Overview

The discussion revolves around the velocity of water in hoses, particularly why it is perceived to be low inside the hose compared to the exit opening. Participants are exploring concepts related to fluid dynamics, specifically the implications of hose diameter on water flow and velocity.

Discussion Character

  • Exploratory, Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants question the relationship between hose diameter and water velocity, with some attempting to clarify how the exit opening size affects flow. Others raise concerns about the implications of low velocity on water movement out of the hose.

Discussion Status

There is an ongoing exploration of the concepts involved, with some participants providing insights into the Bernoulli equation and its relevance to the problem. While there is acknowledgment of certain statements as correct, multiple interpretations of the dynamics at play are being discussed.

Contextual Notes

Some participants reference specific constraints of the problem, such as the focus on pressure energy conversion and the conditions under which kinetic energy can be ignored. There is a noted emphasis on the relationship between pressure and velocity at the outflow opening.

werson tan
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Homework Statement


in the second photo , why the velocity inside the hose is relatively low ? If it is low , the water wouldn't be able to move out of the hose , am I right ?

Homework Equations

The Attempt at a Solution

 

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Did you read the template headers ?

What the writer means is that the exit opening of the hose is considerably smaller than the diameter.
 
BvU said:
Did you read the template headers ?

What the writer means is that the exit opening of the hose is considerably smaller than the diameter.
how it relate to the V1 ?
 
It doesn't. The volume flow is not playing a role in this exercise, where the upper limit of the achievable height is calculated.
 
BvU said:
It doesn't. The volume flow is not playing a role in this exercise, where the upper limit of the achievable height is calculated.
you mean when the diameter in the hose is larger , the velocity of water in the hose is much smller ( almost = 0 ) compared to the velocity of water at the escaping hole ?
 
Bernoulli equation is an energy balance. Here the pressure energy (difference) is converted into gravitational potential energy. The upper limit for height follows if the kinetic energy in the hose can be ignored.

And indeed, at the outflow opening there is mainly kinetic energy.
 
BvU said:
Bernoulli equation is an energy balance. Here the pressure energy (difference) is converted into gravitational potential energy. The upper limit for height follows if the kinetic energy in the hose can be ignored.

And indeed, at the outflow opening there is mainly kinetic energy.
ok , so is my statement in post #5 correct ?
 
I would say: yes it is. You can conclude v2 in the hose is ignored wrt v2 at the outflow opening.

I tried to talk around that a bit, since there is a small issue of what exactly happens at the outflow opening: a high v means a low p
 

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