45kg into PSI

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Offline AVO

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45kg into PSI
« on: 13/02/2009 22:59:33 »
Hi all,

My question is how to convert 45kg into psi? I have used a few online converters which say itís just less than 700psi, can this be true?
If you were to fill a pop bottle up with air using a foot pump which had pressure gage attached to it, and it reads 10psi. Then a person was to stand on the bottle and their weight was 45kg, what would the pressure gage read in psi?
Many thanks for taking the time to read this, I hope someone can help.



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45kg into PSI
« Reply #1 on: 14/02/2009 00:06:45 »
Kilograms is a unit of mass.
psi  is a unit of pressure.
There is no conversion between them because they have different dimensions.
BUT  there are conversion factor from pounds and inches to SI units and then you could work out the initial pressure in Pascals.
You would need to know something of the size of the bottle and possibly its strength (or  possibly assume it is a totally flexible but inelastic envelope) because the final situation, when things have settled down will end up with the weight of the person being balanced by the pressure under the foot (weight over area)  and the tension (taking into account the direction) in the fabric of the bottle.
I think this is a non-trivial problem so you need to ask the questioner a bit more about the model.  They may be after a much simpler answer / ballpark figure and they may be assuming 'certain things'.


Offline Soul Surfer

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45kg into PSI
« Reply #2 on: 14/02/2009 00:19:23 »
To convert your 45kg weight into a pressure you need to know the area over which this 45kg is applied 45kg/square metre is not a very great pressure 45kg per square centimetre is quite high and 45kg per square millimetre is very high indeed for the pop bottle experiment you need to estimate the area of the bottle flattened by the 45kg weight divide that into the 45kg and that will give you the approximate pressure.  You can convert the units just by converting the valued of weight and area as needed
« Last Edit: 14/02/2009 00:22:11 by Soul Surfer »
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