Finding the total pressure acting on a submarine

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SUMMARY

The total pressure acting on a submarine at periscope depth (5 m) and a speed of 30 knots can be calculated using the equation Po = Ps + (1/2)(rho)(V)^2, where rho is the sea-water density (1030 kg/m³). The static pressure (Ps) at this depth is derived from the hydrostatic pressure equation dP = (rho)(g)(dh), which accounts for the water column above the submarine. The mercury manometer will read the total pressure, which includes both static and dynamic components, but the nose of the submarine may experience variations due to the stagnation point. Newton's method can be applied to calculate the lift of the submarine.

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strine07
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Hello I'm having trouble with answering this question: Certain submarines are capable of speeds in excess of 30 knots. What is the total pressure sensed at the nose of a submarine if the vessel is at periscope depth (5 m) and a speed of 30 knots? (Assume a constant sea-water density of 1030 kg/m3.) What height would the captain read on a mercury manometer that sensed this total pressure?
I know the equations Po=Ps + (1/2)(rho)(V)^2 and dP=(rho)(g)(dh) but am having trouble finding the static pressure in order to find the total pressure.
 
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A depth of 0m corresponds to air pressure (~1.013*10^5 N), your equation for dP allows to add the 5m of water between nose and surface.
 
The second equation should be enough. The submarine will experience this pressure over its surface area. So the mercury manometer will sense this pressure. The hard part would be to calculate the "lift" of the submarine, for which you could use Newton's method.
 
Keep in mind that the nose may see a stagnation point, you won't necessarily see the same total pressure (static and dynamic) as other parts of the vessel.
 

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