Submitted by Personhuman815 t3_11e1m71 in explainlikeimfive
More specifically, how do you calculate pressure, then take that and convert to kg/cm2? Thanks (:
Comments
varialectio t1_jaby9ku wrote
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?
Personhuman815 OP t1_jabzb3x wrote
Sorry for not elaborating more. Say I already knew the mass, speed, acceleration, etc of the object
[deleted] t1_jabykyr wrote
[removed]
Personhuman815 OP t1_jabzalu wrote
Sorry for not elaborating more. Say I already knew the mass, speed, acceleration, etc of the object
Any-Growth8158 t1_jae1d91 wrote
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.
Verence17 t1_jabyf4t wrote
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.