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- I know that p = F / S. And if I want to calculate pressure in lb/in2 I have to calculate with mass. That means p = (m * g) / S. But that does not work with lb/in2.

(Sorry for my bad English.)

Hello,

I am trying to understand U.S. customary units (don't ask why I am trying to do this) but when I was calculating pressure to lb/in2 I went into problem. I remember that p = F / S but when you have mass you have to multiply mass by gravitational acceleration to get force. So that means p = (m * g) / S. But when I have m = 10 lb; S = 100 in and g = 393 in/s2 and calculate p = (10 * 393) / 100 it just does not work. But when I remove gravitational acceleration it works. But m is mass and we have to multiply it with gravitational acceleration when we want to know force. I searched on Wikipedia and on Wikipedia is that psi isn't pound per square inch but it's pound-force per square inch. But anyway it is still FORCE. Does someone know how it works?

Hello,

I am trying to understand U.S. customary units (don't ask why I am trying to do this) but when I was calculating pressure to lb/in2 I went into problem. I remember that p = F / S but when you have mass you have to multiply mass by gravitational acceleration to get force. So that means p = (m * g) / S. But when I have m = 10 lb; S = 100 in and g = 393 in/s2 and calculate p = (10 * 393) / 100 it just does not work. But when I remove gravitational acceleration it works. But m is mass and we have to multiply it with gravitational acceleration when we want to know force. I searched on Wikipedia and on Wikipedia is that psi isn't pound per square inch but it's pound-force per square inch. But anyway it is still FORCE. Does someone know how it works?