Physics
Physics
Problem
A large aquarium contains still freshwater. One pressure sensor is mounted flush against a vertical side wall at a depth of below the surface, and a second identical sensor is mounted on the bottom directly beneath the first, also below the surface. Both sensors read the same pressure. Which statement best explains this result? a) Because each sensor supports the same 0.50\,m column of water, the weight of that column produces identical pressures on both sensors. b) At a given depth, fluid pressure acts equally in all directions because molecular collisions are random and isotropic. c) Atmospheric pressure is much larger than the hydrostatic contribution at 0.50\,m depth and is uniform throughout the tank, so both sensors record the same total pressure. d) Hydrostatic pressure acts only vertically; the side sensor merely detects that vertical component at the 0.50\,m depth, giving the same reading as the bottom sensor.Intuitive explanation
The key insight is recognizing that pressure in a fluid depends only on the depth below the surface, not on the shape of the container or the sensor's orientation. Both sensors sit at the same vertical depth (), so they experience the same total pressure—atmospheric pressure plus the weight of water above them. The fact that one is on the wall and one is on the bottom doesn't matter; what counts is how far down each one is in the water column.
Intuitive explanation
The key insight is recognizing that pressure in a fluid depends only on the depth below the surface, not on the shape of the container or the sensor's orientation. Both sensors sit at the same vertical depth (), so they experience the same total pressure—atmospheric pressure plus the weight of water above them. The fact that one is on the wall and one is on the bottom doesn't matter; what counts is how far down each one is in the water column.