A completely filled closed container of water falls freely under gravity. Two points in the water are vertically separated by 1.0 m. Neglecting surface-tension effects, the pressure difference between the two points is N Pa. Find N.
Physics · Fluid Mechanics · question based on variation of pressure
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Question

A completely filled closed container of water falls freely under gravity. Two points in the water are vertically separated by 1.0 m. Neglecting surface-tension effects, the pressure difference between the two points is N Pa. Find N.

Physics · Fluid Mechanics · question based on variation of pressure

G1 Physics · Accepted Answer

In free fall, the container and the water accelerate downward together with acceleration g. In the frame of the container, g(eff) = g−g = 0. Therefore the hydrostatic pressure gradient vanishes: dP/dz = 0. Hence there is no pressure difference due to vertical separation. Thus, N = 0.