Vessel of water under free fall

[AdityaDev]

When a Vessel of water is under free fall and there is a hole in the side of the vessel, why does no water come out of the vessel? (its given in my textbook that pressure exerted on sides of vessel is zero. But what does the horizontal force have to do with the vertically acting force due to gravity?)

 

[DaveC426913]

Water has weight. It pushes down on the water below it, creating horizontal pressure. Under gravitational influence, the water seeks the lowest point of potential energy. It can do this by pouring out the hole.

 

[AdityaDev]

Water has weight. It pushes down on the water below it, creating horizontal pressure. Under gravitational influence, the water seeks the lowest point of potential energy. It can do this by pouring out the hole.

The textbook says water does not flow out.

 

[A.T.]

why does no water come out of the vessel?

Why should it? The vessel falls with the same acceleration as the water, so it's not in its way.

 

[AdityaDev]

Why should it? The vessel falls with the same acceleration as the water, so it's not in its way.

(its in an Indian textbook, so there are grammatical errors)

 

[DaveC426913]

The textbook says water does not flow out.

I was addressing the default state: when the vessel is sitting on a surface.

You asked: "what does the horizontal force have to do with the vertically acting force due to gravity?"
I provided the answer. Under gravity, the water tries to squeeze horizontally.

So, with that part answered, does it now make more sense why the water would not flow out once gravity is neutralized?

 

[AdityaDev]

Understood.

 

[A.T.]

View attachment 80726

There is no pressure due to the weight of the water, because the weight is not supported by the vessel (the vessel falls itself). There could still be pressure if the vessel is pressurized.

 

[DaveC426913]

View attachment 80726

This does not answer A.T.'s question.

Why should the water come out of the hole while the vessel AND water are freely falling?

 

[AdityaDev]

This does not answer A.T.'s question.

Why should the water come out of the hole while the vessel AND water are freely falling?

It doesn't right?

 

[DaveC426913]

It doesn't right?

Well, you know that, having been told by the textbook. But do you now understand why?

 

[AdityaDev]

Well, you know that, having been told by the textbook. But do you now understand why?

Under free fall, if you consider an arbitrary cylinder of length y like this:

From Newtons laws, $\Delta P.\Delta S+W=mg$
Then $(P_1-P_2)\Delta S+y\Delta S\sigma g=y\Delta S\sigma g$, sigma is the density of liquid. The force acting are due to weight and due to pressure difference.
So, $P_1-P_2=0$
hence, $P_1=P_2$
So there is no pressure difference between 2 levels of the liquid.

 

[AdityaDev]

I don't know if what i did is correct, but it does make sense and i have used nothing other than Newton's laws. Please verify this.