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Pressure per square inch to pressure per square foot

  1. Apr 29, 2015 #1
    Heya guys, I and some colleges were discussing pounds per square and pounds per square foot and I wonder if you can help me with an answer, I would be grateful.

    So the question is, what is pounds per square inch relative to pounds per square foot?

    For example, if I had some flooring installed in my apartment that had a pounds per square inch pressure resistance of say 1000 pounds per square inch, would this also suggest it has a pressure resistance of 144000 pounds per square inch?

    I thought you would just multiply by 144, due to there being 144 square inches in a square foot to find the pressure resistance per square foot.

    By pressure resistance I mean could I place something far heavier as long as it occupied a square foot of flooring than I could place the same weight in a square inch?

    Thank you for any answers, if there are any resources you have that I could take a look at so I can show my friends as well that would be great!
  2. jcsd
  3. Apr 29, 2015 #2
    You got your numbers right but for some reason you said "inch" when I think you meant "foot" there.

    I think I understand what you are trying to say here. Yes, you could place something heavier in a larger area so long as the pressure resistance was not exceeded.
  4. Apr 29, 2015 #3


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    Staff: Mentor

    You mean per square foot.

    That's correct.

    Just to be clear, the units have nothing to do with how big the object is. It is only convenience that makes one set of units "better" than another. If the flooring can withstand 1000 pounds per square inch, then you could put a 1000 pound weight provided that the contact it makes on the floor is at least one square inch, or you could put something weighing 100 pounds with a footprint of 1/100 th square inch. Note also that their might be a maximum weight: even if the flooring can withstand 144000 pounds per square foot, it doesn't mean that the floor can withstand a total weight of 144000 pounds.
  5. Apr 29, 2015 #4
    Yes sorry, typo on that square inch part. So essentially its correct then?

    So say, using the same example I have an object that exerts 144000 pounds per square foot of pressure and put it on my floor that can take the pressure of 1000 pounds per square inch (Which based on what has been said is equal to 144000 pounds per square foot) what would happen?

    Further what would happen if say my floor could take 2000 pounds per square inch? I guess what I am asking is would an object that exerts too much pressure for a square inch to sustain but if it can be placed in a way that its touching a square foot, would likely support it? Like say a heavy ornament that if placed upright has a base that is a few square inches but if placed on its side, has a surface area nearing a square foot.

    Sorry if my examples are getting confusing, I hope my intent is somewhat clear though :smile:
  6. Apr 29, 2015 #5


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    Staff: Mentor

    That sounds correct. I good way to think about it is stilettos: even the lightest of women can do some nasty damage to a floor when wearing stilettos, but you wouldn't think twice of letting her walk with flat-footed shoes.
  7. Apr 29, 2015 #6
    Thanks guys, much obliged especially since I did not think I would get replies so fast as well! :woot:. Are there any online papers, websites or what not that I could use to explain this to my friends?
  8. Apr 29, 2015 #7


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    Staff: Mentor

    It's a fairly straightforward units issue, so I"m not sure if any references exist.

    I will ask though: where did you get the numbers you are using? They sound extraordinarily high for the load bearing capability of a floor.
  9. Apr 29, 2015 #8
    I just used any number I could think of, I used 1000 pounds since it sounded simple, I just wanted to know whether you could find the pounds per square foot by multiplying the pounds per square inches by 144.
  10. Apr 29, 2015 #9


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    Science Advisor

    Have you tried typing "pounds per square inch to pounds per square foot" into Google?
  11. Apr 29, 2015 #10
    Aye but I wanted to make sure I was doing it in the right sense. Someone I know seemed to think that you cant just multiply pressure per square mm, or square inch to scale the numbers up to square foot, square meter etc etc.
  12. Apr 29, 2015 #11
    I would think (hope) that your friend would be amenable to the argument that 144 square tiles the size of a square inch each can be arranged into one big tile of a square foot. If each of those tiles had a pound sitting on it, clearly the whole thing now has 144 pounds sitting on it!
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