Find force when given air pressure and volume

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Homework Help Overview

The problem involves calculating the total force acting on a vertical surface of a reservoir dam, given the dimensions of the dam and the air pressure. The context is related to fluid mechanics, specifically the behavior of pressure in a fluid at rest.

Discussion Character

  • Exploratory, Assumption checking

Approaches and Questions Raised

  • Participants discuss the concept of average pressure and its calculation based on the varying pressure with depth. There is a mention of relevant equations, but the original poster expresses uncertainty about their application.

Discussion Status

Some participants have provided hints regarding the calculation of average pressure, and there is acknowledgment of the linear variation of pressure with depth. However, the original poster's understanding of how to apply these concepts remains incomplete.

Contextual Notes

The original poster indicates this problem is part of an assignment, suggesting a time constraint. There is also a reference to a specific textbook, which may imply reliance on the material covered therein.

physics1007
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The vertical surface of a reservoir dam that is in contact with the water is 170 m wide and 10 m high. The air pressure is one atmosphere. Find the magnitude of the total force acting on this surface in a completely filled reservoir. (Hint: The pressure varies linearly with depth, so you must use an average pressure.)

Could anyone please help me with this. Its part of an assignment due. The question comes from "Physics 7th edition by Cutnell" Chapter 11 problem 26.

I know that Pressure=Force/Area but no idea how to solve this problem. I also know the p2=p1+pgh equation but don't know if i need this.:rolleyes:
 
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The hint shows you the way. What's the average pressure? (What's the pressure at the water surface? At the bottom of the dam?)
 
OK. Thanks. I got the right answer.
 
Last edited:
Since pressure varies linearly with height, the average pressure will be smack in the middle between the two extremes.
 

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