How is pressure converted to force in a large enclosed surface area?

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Discussion Overview

The discussion revolves around the relationship between pressure and force applied to a large enclosed surface area, particularly in the context of a chamber experiencing a specific water column pressure at high temperatures. Participants explore how to calculate the force exerted on the chamber's shell based on the pressure and surface area involved.

Discussion Character

  • Technical explanation
  • Mathematical reasoning
  • Debate/contested

Main Points Raised

  • One participant describes a process that generates a water column pressure of 1.7 inches in a chamber and seeks to calculate the force on the shell using the formula F = P * A.
  • Another participant reiterates the formula F = P * A and questions whether the force exerted by a 1 psi pressure in a smaller cube (12 inches) is less than that in a larger cube (36 inches), suggesting that the larger area might produce less force.
  • A different participant provides calculations showing that a 12-inch cube pressurized to 1 psi results in 864 lb of force, while a 36-inch cube at the same pressure results in 7776 lb of force, arguing that more area requires more force.
  • One participant uses the analogy of a sailboat, stating that a larger sail area produces more force at the same wind speed, implying that larger containers at equal pressure will exert more total force due to their larger surface areas.

Areas of Agreement / Disagreement

There is disagreement regarding the relationship between pressure, area, and force. Some participants assert that larger areas result in greater total force, while others question this by suggesting that the force per unit area remains constant regardless of the size of the area.

Contextual Notes

Participants have not reached a consensus on the interpretation of force exerted by different sized containers at the same pressure, leading to unresolved questions about the implications of pressure and area on force calculations.

mjacobs535
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I have a "process" that creates approx. 1.7" of water column throughout a large enclosed surface area, at temperatures ranging from 1500 to 2250 F. I am trying to show the actual force applied to the shell over a large surface area from the known measurment of pressure. For instance, I have 1.7" water column, at 1560 F, in a chamber approx. 15ft x 10ft x 65ft. how can I show the force applied to the entire shell?
 
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mjacobs535 said:
I have a "process" that creates approx. 1.7" of water column throughout a large enclosed surface area, at temperatures ranging from 1500 to 2250 F. I am trying to show the actual force applied to the shell over a large surface area from the known measurment of pressure. For instance, I have 1.7" water column, at 1560 F, in a chamber approx. 15ft x 10ft x 65ft. how can I show the force applied to the entire shell?

F = P * A
F Force
P Pressure
A Area
 
NUCENG said:
F = P * A
F Force
P Pressure
A Area
I understand that, what I am trying to understand is, if you have for instance 1 psi in a 12" cube, is the outward exerted force less than that of a 36" cube with 1 psi? It seems that the larger area would have less force than the smaller area at the same pressurization.
 
F=P*A

Take 2D:
1*(12)^2 = 144 lb of force
1*(36)^2 = 1296 lb of force

Pressure is the result of force over an area. If you have more square inches, you need more pounds.

For 3d just multiply by 6
12" cube pressurized to 1psi has 864 lb of force.
36" cube pressurized to 1psi has 7776 lb of force.
 
mjacobs535 said:
I understand that, what I am trying to understand is, if you have for instance 1 psi in a 12" cube, is the outward exerted force less than that of a 36" cube with 1 psi? It seems that the larger area would have less force than the smaller area at the same pressurization.

Think of a sailboat. A larger sail area produces more force at the same wind speed. Two containers at equal pressure and different surface areas will produce more force on the container with the larger surface area. The pressures (force per unit area) are the same but the areas are different so the total force is different.
 

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