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Horizontal force across a partition

  • Thread starter Parsifal1
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  • #1
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Homework Statement


Find the horizontal force across the partition in a water tank with two compartments, one filled with water to x height and the other with water to y height. I've worked out the thrust acting on the partition as a result of density, height, gravity and average depth, so I have two horizontal vectors, with which to find the total horizontal force.

Homework Equations


F=PaA
P=pgh
F=pgha

The Attempt at a Solution


(sum) Fx=(Force from oil) - (Force from water). Problem is I don't know which force is in which direction relative to the partition. The only solution I can see, which would make sense is adding the two forces together. Is this correct?
 

Answers and Replies

  • #2
Simon Bridge
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I'm confused.
You write,
(sum) Fx=(Force from oil) - (Force from water).
... but "oil" is not mentioned in the problem statement, which says:
... two compartments, one filled with water to x height and the other with water to y height.
... just water on each side of the partition.

Looking at those heights:
Lets say y>x, then what else is in the tank at height h: y-x<h<y? What about when h>y?

Problem is I don't know which force is in which direction relative to the partition.
... but your problem statement says:
Find the horizontal force across the partition
... which direction is "horizontal"?
 
  • #3
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The question says there is a tank which has a vertical partition across the width. There are two compartments in the tank, one contains water the other oil. I have worked out the hydrostatic force each liquid exerts on the partition. Now I have to find the 'horizontal force on the partition', Do I add the two forces together?
 
  • #4
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3
I'm confused.
You write, ... but "oil" is not mentioned in the problem statement, which says: ... just water on each side of the partition.

Looking at those heights:
Lets say y>x, then what else is in the tank at height h: y-x<h<y? What about when h>y?


... but your problem statement says: ... which direction is "horizontal"?
Horizontal parallel to the base of the tank, normal to the vertical partition, I assume.
 
  • #5
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Does the horizontal resultant force equal the difference between the two opposing forces?
 
  • #6
Simon Bridge
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The resultant force is the vector sum of all the forces ... the horizontal resultant force is the horizontal component of the resultant force.
In your case - where do the forces come from? Where do the forces act?

I am making some assumptions about what the question is really asking ... technically the net horizontal force on the partition must be zero since it is not accelerating. I am guessing the question wants the net force due to the difference in pressure on each side.
 
Last edited:

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