# Water in hose

1. Jan 24, 2016

### werson tan

1. The problem statement, all variables and given/known data
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 ?

2. Relevant equations

3. The attempt at a solution

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2. Jan 24, 2016

### BvU

What the writer means is that the exit opening of the hose is considerably smaller than the diameter.

3. Jan 24, 2016

### werson tan

how it relate to the V1 ?

4. Jan 24, 2016

### BvU

It doesn't. The volume flow is not playing a role in this exercise, where the upper limit of the achievable height is calculated.

5. Jan 24, 2016

### werson tan

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 ?

6. Jan 25, 2016

### BvU

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.

7. Jan 25, 2016

### werson tan

ok , so is my statement in post #5 correct ?

8. Jan 25, 2016

### BvU

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