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More accurately, the pressure at depth is found by multiplying the
water density by both the acceleration due to gravity and the height
of the water column. In metric, this is done as: Pressure [Pa] = Density [kg/m^3] * g [m/s^2] * h where density is 1000 kg/m^3 for fresh water or 1025 kg/m^3 for sea water, and g is 9.80665 m/s^2 for standard gravity. While the formal imperial unit for mass is the slug, the common imperial unit for mass is the pound_mass, which is simply defined as the mass weighing one pound_force under standard gravity (32.174 ft/s^2). If you wanted to find pressure under different gravity / acceleration conditions, you would need to work in slugs or divide by standard gravity to go backwards. With the common units, you don't need to consider gravity as it is included in the unit. Thus, the Imperial calculation is: Pressure [pounds_force/ft^2] = density [pounds_mass/ft^3] * h where density is 62.4 pounds_mass/ft^3 for fresh water, or 64 pounds_mass/ft^3 for sea water. The result is in pounds_force per square foot, so divide by 144 to get psi. -Sean On 11/09/2011 11:04 AM, Scott Waters wrote:
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