# What is the reason for the hydrostatic paradox

## Physics compact 5, special issue

Forces in liquids and gases at rest 3 16 Mechanics 1 RG 5 and G 6.1 Hydrostatic pressure Under the influence of gravity, the hydrostatic pressure p (hydrostatic pressure) prevails in every liquid. The hydrostatic pressure is also called heavy pressure. The hydrostatic pressure is created by the weight of the liquid column above its base area A. It is noteworthy, however, that the hydrostatic pressure not only acts vertically but, like the static pressure, in accordance with Pascal's law on all sides (side pressure). 3.2 Pressure p Depth below the surface h The gravitational pressure increases with depth. p h Fig. 16.1 The pressure of gravity increases with depth. p = t · g · h p… hydrostatic pressure t… density of the liquid g… acceleration due to gravity h… depth below the surface Unit: [p] = Pa = N · m −2 Hydrostatic pressure ∆ h p 1 p 2 Fig. 16.2 Mercury manometer. The hydrostatic pressure is used in the mercury manometer to measure pressure. The pressure difference D p = p 1 -p 2 can be read from the height difference D h. Fig. 16.3 Pascal's experiment Fig. 16.4 Hydrostatic paradox: The water is the same level in connected vessels. A1 Interpret the formula for hydrostatic pressure! A2 Derive the formula for the hydrostatic pressure! A3 A steel diving ball with a diameter of 2m is lowered to a depth of 1000m. Calculate the amount of force that acts on the surface of the sphere! What would have to be considered for an exact calculation? A4 Think how the side pressure affects the shape of dams! A5 A cargo ship has an immersion depth of 10 m. Calculate the hydrostatic pressure on the underside of the ship and give it in cash! Compare this pressure with normal air pressure. W2 W2 W2 E2 W2 For testing purposes only - property of publisher öbv