The pressure in a liquid

Analyze the question: We are asked which statement correctly describes pressure in a liquid.

Concept: The pressure at a point in a liquid at rest is given by

P = hρg

where h is the depth, ρ is the density of the liquid, and g is the acceleration due to gravity. Two key facts follow from this:

1. Pressure depends on depth, so it increases as you go deeper.
2. At any given point, the liquid pushes equally in all directions (up, down, and sideways). This is why a pressure gauge placed at one depth gives the same reading however it is turned.

Checking each option:

• A. Same at all points in the liquid. False. Pressure changes with depth (P = hρg), so points at different depths have different pressures.
• B. Decreases with depth. False. Pressure increases with depth. That is why dams are built thicker at the bottom.
• C. Same in all directions at a given point. True. At a fixed point in a liquid at rest, the pressure acts equally in every direction.
• D. Equal to atmospheric pressure. False. The total pressure at depth h is atmospheric pressure plus hρg, so it is greater than atmospheric pressure, except right at the surface.

Answer: The correct option is C.

Exam tip: Remember the phrase "Deeper means higher pressure, and at a point it pushes equally everywhere." Whenever an option says pressure "decreases with depth" or is "the same everywhere" in a liquid, it is almost certainly a distractor.