In engineering when we need to measure something, it is often inconvenient or sometimes impossible to directly measure the thing we need to know. Therefore we often measure something else, and use a mathematical relationship to calculate the thing we want. Explain how one or more pressure gauges could be used to determine the depth of water in a tank or pool. In your explanation, describe the location$($s$)$ where pressure gauge$($s$)$ would be placed and how the mechanical energy equation $($Eq$.7\mathrm{.}8$b$)$ would allow the desired property to be calculated from pressure measurement.