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How to Calculate Water Pressure at Depth

The scientific term used for the pressure exerted on an object at depth by all types of fluid, including water, is fluid pressure. In order to find the water pressure at depth, you'll need calculate the current fluid pressure value. Fluid pressure can be calculated using this formula: Pressure = Atmosphere Pressure + (R x G x H). Where "R" is the density of the fluid, "G" is the acceleration of gravity on earth and "H" is the height of the fluid, in meters above the you. The density of sea water is 1.03 X 10^3 kg/m^3, the atmospheric pressure on earth is 1.01 x 10^5 N/m^2 and the gravitational pull is 9.8 m/s^2. Therefore, sea water pressure in kPa = 1.01 x 10^5 N/m^2 + (1.03 x10^3 kg/m^3 x 9.8 m/s^2 x height in meters).

Things You'll Need

Depth gauge
Laminated card
Underwater writing board

Instructions

- 1
  Sink to the desired depth and note the depth reading on your depth gauge. Take out you writing board. If your depth reading is in feet, convert to metric by multiplying the foot value by 0.3048, using your board to write out your calculations.
- 2
  Take out your laminated data sheet containing all known variable values and formulas. Write out the depth formula on your writing board and insert all known variables. Insert the metric depth value for the variable "Height." In the formula, total pressure in kPa = 1.01 x 10^5 N/m^2 + (1.03 x10^3 kg/m^3 x 9.8 m/s^2 x Height in meters).
- 3
  Calculate and solve for "Total Pressure." This the water pressure at your current depth expressed in kPa.
- 4
  Divide the kPa value by 100 to get your current bar value. One bar is equal to the pressure of the entire earth's atmosphere on a body standing at ground level. Water is so dense that for every 33 feet you sink, you increase your bar value by one, therefore a depth of 99 feet, you are experiencing the weight of four atmospheres, three of which are from the water alone.

Nature