Consider a tank containing liquid and moving vertically upwards with a uniform acceleration.

Since the tank is subjected t an acceleration in the vertical direction only, therefore the liquid surface will remain horizontal.

Now consider a small column of liquid of height h and area dA as shown in


The force acting on the liquid column s the weight of liquid column W acting vertically downwards, acceleration force F and pressure force exerted by the liquid on the column.

Applying  Newton’s second law of motion,

Σ Fy = m a_y

P - W = m a_y

p.dA - γhdA   = γhdA / g. a

p.dA = γhdA  / g .a + γhdA  

p = γh (a/g + 1)

If the liquid is moving vertically downward with a uniform acceleration, the pressure will be,

p = γh (1 -a/g)

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