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Hydrostatic pressure is the pressure exerted by a fluid at equilibrium due to the gravitational pull acting on it. In the context of a body of water, this pressure is induced by the weight of the water column above a given point. To find hydrostatic pressure, we use the formula: \[ P_{w} = \rho gh \] where:

• \(\rho\) is the density of the fluid.
• \(g\) is the acceleration due to gravity.
• \(h\) is the depth or height of the fluid column.

By inserting the values given in the problem, such as the water density of \(1.00 \times 10^{3} \text{ kg/m}^{3}\), gravity \(9.8 \text{ m/s}^{2}\), and the depth \(27.5 \text{ m}\), we can compute the pressure exerted solely by the water above. This understanding of hydrostatic pressure is crucial when working with fluids, and especially in applications like dam constructions and evaluating underwater pressures.

Absolute pressure represents the total pressure at a given point in a fluid, comprised of both atmospheric pressure and the hydrostatic pressure. It is essential in understanding scenarios where the fluid is not just acting under its own weight but is also influenced by the surrounding atmospheric conditions. The absolute pressure \(P\) at a particular depth in a lake, is computed as follows:\[ P = P_{\text{atm}} + P_{w} \] Here, \(P_{\text{atm}}\) is the atmospheric pressure above the fluid surface (given as \(101.3 \text{ kPa}\) or \(101.3 \times 10^{3} \text{ Pa}\) in this case), and \(P_{w}\) is the hydrostatic pressure obtained from the earlier calculation. Summing these pressures gives the absolute pressure, illustrating how pressures add up in fluid systems, factoring in both local fluid weights and external pressure influences.

When immersed in a fluid, objects experience pressure exerted over their surface area, creating a force. To determine the force on an object, such as a window, we first calculate the area of the object's surface where the force is applied. For a circular window, the area \(A\) can be obtained using the formula: \[ A = \frac{\pi d^2}{4} \] With a diameter \(d\) of \(0.35 \text{ m}\), one substitutes this value into the formula to ascertain the window's area. Once the area is known, the force \(F\) exerted by the water on this area is found through: \[ F = PA \] where \(P\) is the already calculated absolute pressure. This calculation highlights how pressures translate physically into forces, important for designing structures that encounter fluid forces, like submarines and underwater observatories.