PHYSICS · Single correct · AP · Physics 1: Algebra-based · Fluids · Fluids
Problem
A large aquarium contains still freshwater. One pressure sensor is mounted flush against a vertical side wall at a depth of 0.50m below the surface, and a second identical sensor is mounted on the bottom directly beneath the first, also 0.50m 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.