Simple Static Pressure problem, with units

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Homework Help Overview

The discussion revolves around a static pressure problem involving a bathtub filled with water to a depth of 20 inches. Participants are tasked with determining the pressure at the bottom of the bathtub in both absolute and gauge pressure units.

Discussion Character

  • Exploratory, Assumption checking, Mathematical reasoning

Approaches and Questions Raised

  • The original poster attempts to use the equation P=pgh to calculate gauge pressure but struggles with unit conversion to psi. Some participants suggest converting the depth to meters for SI unit consistency, while others question how to eliminate the /s² from the final answer.

Discussion Status

Participants are exploring different unit systems and discussing the implications of using various definitions of pressure. Suggestions have been made regarding the weight of water and its relation to pressure calculations, but no consensus has been reached on a specific method or solution.

Contextual Notes

There is mention of the challenge in converting units and the need to understand the definitions of pressure units. The original poster expresses uncertainty about the conversion process and the resulting units.

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Homework Statement


Hi I'm having trouble solving this physics problem if anyone can help it would be greatly appreciated !

Static pressure problem: A bathtub contains water to a depth of 20 inches. Determine the pressure at the bottom of the bathtub in both [psia] and [psig] (a being absolute pressure and g being gauge pressure)


Homework Equations


im using P=pgh

The Attempt at a Solution


what I've tried doing was to find gauge pressure first: P=pgh=(1.94slug/ft^3)(32.2ft/s^2)(1.67ft). I got the 1.67 feet from converting 20 inches to feet. the answer i get is 104.11slug/s^2 but they want it in psi or lb/in^2 and i am having trouble converting these units =[
 
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Why don't you just convert the initial 20 inches to meters then solve for the standard SI units?
 
Well the problem is that i don't know how to get rid of the /s^2 in my final answer and even if i use the standard SI units ill still come up with an answer that has /s^2
 
That's the acceleration…s^2 is an SI unit.
 
Also…

look at the definition of what a pound actually is (in terms of units). That should fix things.
 
Instead of using different unit systems, 1 cu. ft. of fresh water weighs about 62.4 pounds. Knowing that number, you should be able to find psi given the depth of water in the bath tub.
 

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