Given:

• Depth below sea surface = 60 ft
• Specific Gravity (SG) of seawater = 1.022
• Barometric pressure = 29.2 in Hg (inches of mercury)

Find:

The pressure in psi (pounds per square inch) at 60 ft below the surface of the sea.

Solution:

1. Convert barometric pressure to psi:

   We first need to convert the barometric pressure from inches of mercury (in Hg) to psi.

   • 1 in Hg = 0.4912 psi
   • Barometric pressure = $29.2 \, \text{in Hg}$

   $\text{Barometric pressure (in psi)} = 29.2 \times 0.4912 = 14.34 \, \text{psi}$

2. Determine the density of seawater:

   The density of seawater is the product of the specific gravity (SG) and the density of freshwater, which is approximately $62.4 \, \text{lb/ft}^3$ (pounds per cubic foot). $\text{Density of seawater} = 1.022 \times 62.4 = 63.77 \, \text{lb/ft}^3$

3. Calculate the pressure due to water column:

   The pressure exerted by a water column is given by the equation: $\text{Pressure (in psi)} = \frac{\text{Depth (in feet)} \times \text{Density (in lb/ft}^3\text{)}}{144}$ where 144 is the conversion factor from square inches to square feet.

   Substituting the values: $\text{Pressure due to water column} = \frac{60 \times 63.77}{144} = 26.57 \, \text{psi}$

4. Total pressure at 60 ft below the surface:

   The total pressure is the sum of the barometric pressure and the pressure due to the water column: $\text{Total pressure} = 14.34 \, \text{psi} + 26.57 \, \text{psi} = 40.91 \, \text{psi}$

Answer:

The pressure 60 feet below the surface of the sea is 40.91 psi.

Would you like more details on any step?

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Here are some related questions:

1. How does specific gravity affect the pressure calculation?
2. What would the pressure be at 100 ft depth instead?
3. How does barometric pressure influence total underwater pressure?
4. Can this method be applied to different liquids like oil or alcohol?
5. How do temperature variations affect seawater density and pressure?

Tip: Always ensure to use accurate conversion factors when working with units like psi and inches of mercury.