Answer by
Qman (7)

Water is an incompressible liquid, so the pressure equals the sum of the reference pressure (since this is the bottom of a flat tank, it is zero Pascals) plus the product of the density of water (1000 kilograms per meter cubed) times acceleration due to gravity (9. 8 meters per second squared) times height (4 meters), which equals 39200 Pascals.