Understanding the Force of Two Cubes

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SUMMARY

The discussion centers on calculating the force exerted by a solid cube under atmospheric pressure. The pressure outside the cube is 1.01 × 10^5 Pa, leading to a force calculation of F = pA, where A is the area of one face of the cube, resulting in a force of 6.3 × 10^3 N. A participant questions why only one cube's area is used in the calculation, suggesting that both cubes should be considered. However, the correct approach is to analyze the forces acting on a single cube, specifically in relation to the missing face.

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  • Familiarity with the formula for calculating force (F = pA).
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  • Basic geometry to calculate the area of a cube's face.
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Homework Statement
Two hollow cubes of side 25 cm with one face missing are placed
together at the missing face. The air inside the solid
formed is pumped out. Determine the force that is necessary to
separate the cubes.
Relevant Equations
P=F/A
The solution is :

The pressure inside the solid is zero and outside it equals atmospheric pressure, 1.01 × 10^5 Pa.

Thus, the force is given by: F =pA = 1.01 × 10^5 × (0.25)^2 = 6.3 × 10^3 N

I do not understand why only the area of one cube is used in the solution, should it not be the area of both cubes e.g. Area of 2 cubes = 2 x (0.25)^2?
 
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This is analogous to a rope being pulled with force F at each end. Is the tension F or 2F?
Just consider one cube. What forces act on it in the direction normal to the missing face?
 
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