 Welcome to hydrostatic pressure. The pressure exerted by a material in a vessel is directly proportional to its height times its density. The force that is produced by the material is called hydrostatic pressure or head pressure. The formula for hydrostatic pressure is hydrostatic pressure equals height multiplied by density. As the height of the material changes, there is a proportional change in pressure. By placing a pressure gauge at the bottom of the vessel, the level of the material can be determined by using the following formula. Height equals pressure divided by density. Water is an example of a liquid stored in a vessel. A common unit of measurement for water pressure is pounds per square inch. The weight density of water is 0.036 pounds per cubic inch. Suppose the pressure gauge at the bottom of a vessel containing water reads 1.8 psi. To determine the level of the water, we use the following calculation. The height level equals 1.8 psi, the pressure, divided by 0.036 pounds per cubic inch, the density. This equals 50 inches of water. Hydrostatic readings can only be taken in an open container. If measurements are taken in a pressurized vessel, the pressure created by the airspace above the surface will add to the pressure of the liquid and cause a false reading. Now, let's check your understanding. Please pause the video if you need more time to answer the questions. Question 1. Hydrostatic pressure is determined by the density and height of the material in the vessel. Question 2. The hydrostatic pressure in an open vessel can determine the level of a liquid. Question 3. Knowing that the density of one cubic inch of water is 0.036 pounds per cubic inch, what is the level of water in inches if the hydrostatic pressure at the bottom of the vessel reads 2.7 psi? The correct answer is 75 inches. Congratulations! You have completed this activity, hydrostatic pressure.