91Ó°ÊÓ

Fluid statics, often known as hydrostatics, is a branch of fluid mechanics that investigates the state of balance of floating and submerged body, as well as the pressure in a fluid, or imposed by a fluid, on an immersed body.

The pressure due to the weight of air above a specific height, is atmospheric pressure. Because of the large-scale movement of the atmosphere generated by the Earth's rotation, atmospheric pressure near the Earth's surface varies slightly (creating weather "highs" and "lows").

The average pressure at sea level, on the other hand, is determined by the standard atmospheric pressure ${\mathbf{\text{P}}}_{\mathbf{a}\mathbf{t}\mathbf{m}}$, which is measured to be

$$\begin{gathered} \mathbf{1}\mathit{a}\mathit{t}\mathit{m}\mathit{o}\mathit{s}\mathit{p}\mathit{h}\mathit{e}\mathit{r}\mathit{e}\left(atm\right)\mathbf{=}{\mathbf{\text{P}}}_{\mathbf{a}\mathbf{t}\mathbf{m}} \\ \mathbf{=}\mathbf{1}\mathbf{.}\mathbf{01}\mathbf{×}{\mathbf{10}}^{\mathbf{5}}\mathit{N}\mathbf{/}{\mathit{m}}^{\mathbf{2}} \\ \mathbf{=}\mathbf{101}\mathit{k}\mathit{P}\mathit{a}\mathbf{.} \end{gathered}$$

Because atmospheric pressure is equally balanced of the dam, it cancels out.

As a result, there is no net force acting on the dam due to air pressure.

${\mathit{P}}_{\mathbf{o}\mathbf{u}\mathbf{t}}\mathbf{=}{\mathit{P}}_{\mathbf{i}\mathbf{n}}$

On both sides of the dam, air pressure acts. At the same levels, the atmospheric pressure has the same magnitude.

The atmospheric pressure on the opposite side of the dam is in the opposite direction.

Therefore, the dam's net force owing to air pressure is zero.