PSI question

[futbalfantic]

Main Question or Discussion Point

I have a 39"x75"x0.75" area that has 180lbs resting ontop of it. According to P=F/A or P=180lbs/2,925 I^2 therefore P=0.0615.... If a tube comes off of the side of the "box" that is 0.5" inside diameter would this have a pressure of 0.0615 or would I find this pressure some other way?

 

[AlephZero]

If the sides of the box are completely flexible (for example the "box" is just a sealed bag full of air) , then yes. This is how car tires support the weight of the car.

If the box has any stiffness, then some of the 180 lbf will be supported by the forces in the sides. If the box is stiff enough so it doesn't bend much, most likely nearly all the 180lbf would be suppored by the sides, and the change in pressure would be very small.

The diameter of the tube is irrelevant.

 

[futbalfantic]

Yeah I was thinking of a sealed bag full of air.