More specifically, how do you calculate pressure, then take that and convert to kg/cm2? Thanks (:

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varialectio t1_jaby9ku wrote on February 28, 2023 at 9:27 AM

#2,096,940

Calculate from what?

Do you mean take a reading from a gauge in one set of units and convert to kg/cm^2 ?

Or calculate from first principles like gas laws or kinetic theory?

Verence17 t1_jabyf4t wrote on February 28, 2023 at 9:29 AM

#2,096,973

Pressure is defined as force per m^(2). So you can just get a piston of known size (say, 1 cm^(2)), check the force pushing on it, divide the force by size and then convert as you wish.

Also, strictly speaking kg/cm^(2) isn't a physically correct unit of pressure, it's implied that weight in normal gravity is used. "1 kg of force" is actually 1 kg * g (free fall acceleration on Earth, ~9.8 m/s^(2)), so 9.8 N of force.

[deleted] t1_jabykyr wrote on February 28, 2023 at 9:31 AM

#2,097,013

[removed]

Personhuman815 OP t1_jabzalu wrote on February 28, 2023 at 9:42 AM

#2,097,182

Sorry for not elaborating more. Say I already knew the mass, speed, acceleration, etc of the object

Personhuman815 OP t1_jabzb3x wrote on February 28, 2023 at 9:42 AM

#2,097,188

Replying to varialectio (#2,096,940)

Sorry for not elaborating more. Say I already knew the mass, speed, acceleration, etc of the object

Any-Growth8158 t1_jae1d91 wrote on February 28, 2023 at 7:34 PM

#2,120,192

Replying to Personhuman815 (#2,097,182)

The speed has nothing to do with calculating pressure. You need to know the mass, acceleration, and area. Furthermore, while pressure itself is a scalar, for non-simple geometries you need to know the vectors of the acceleration and area.

Most people will tell you that pressure is force divided by the area. This is true, but is making an important assumption--the force is normal to unit area.

If you had a square of 1 m^2 and exerted a force of 10 N over its entire area, what is the pressure? The answer is we can not determine from the information provided. If the force is normal to the square then the pressure is 10N / 1m^2 = 10 N/m^2. If the force is inclined at a 45 degree angle then the pressure is 10N*cos(pi/4) / 1 m^2 = 10sqrt(2)/2 N/m^2.

Things get even more complicated if the force is not evenly distributed in which case you'll be doing some integration.