Hydrostatic pressure at a depth h in a fluid of density ρ is given by:

P = ρg/h P = ρgh P = ρ/gh P = gh/ρ

A diver descends to 10 m depth in seawater (density ≈ 1025 kg/m³, g = 9.81 m/s²). The gauge pressure at that depth is approximately:

About 10 Pa (negligible) About 1,025 Pa (about 1% of an atmosphere) About 100,500 Pa (roughly 1 additional atmosphere) About 1,000,000 Pa (about 10 atmospheres)

Archimedes' principle states that the buoyant force on an object equals:

The weight of the object itself The weight of fluid displaced by the object The pressure at the bottom of the object multiplied by its surface area The volume of the object multiplied by atmospheric pressure

Steel has a density of about 7,800 kg/m³ — far greater than water's 1,000 kg/m³. Why does a steel ship float?

Seawater is denser than freshwater, providing extra buoyancy Steel treated with anti-corrosion coatings becomes less dense than water The ship's hollow hull displaces a volume of water whose weight exceeds the total weight of the ship The ship's engine generates an upward thrust that supplements buoyancy

The Plimsoll line marked on a ship's hull indicates:

The ship's build year and registration port The maximum safe loading depth — the waterline must not exceed this mark The point below which the hull is reinforced against pressure The location of the ship's centre of gravity

A ship's metacentre is the point about which the vessel rotates when it tilts. For a stable ship, the metacentre must be:

Below the ship's centre of gravity At the same height as the centre of gravity Above the ship's centre of gravity At the waterline regardless of cargo loading

How does a submarine dive to a greater depth?

It uses downward-pointing thrusters to push itself below the surface It floods ballast tanks with seawater, increasing the submarine's overall density until it exceeds that of seawater It releases lead weights from the keel to reduce buoyancy It compresses its internal air supply to shrink the hull volume

A submarine achieves neutral buoyancy at its operating depth. This means:

The submarine can travel at maximum speed without resistance The submarine's propellers are generating exactly enough thrust to maintain depth The submarine's weight exactly equals the weight of seawater it displaces, so it neither rises nor sinks The external water pressure equals the internal air pressure inside the hull

Why does hydrostatic pressure increase toward the base of a dam?

Water flows faster near the base, creating higher dynamic pressure Greater depth means more water above, so the weight of fluid pressing down is larger The dam wall curves inward at the base, concentrating pressure there Sediment at the base increases the fluid density near the dam floor

An arch dam (curved in the horizontal plane) transfers the water load primarily to:

The riverbed directly below the dam The canyon walls (abutments) on either side of the river Steel tension cables anchored deep in the foundation Downstream buttress walls spaced at regular intervals

Hydraulic head is used by water-supply engineers to represent pressure as:

The speed of water flowing through a pipe at a given pressure The maximum pressure a pipe can withstand before bursting The equivalent height of a water column that would produce the same pressure The ratio of water pressure to atmospheric pressure

A canal lock raises and lowers boats between two water levels. What principle allows it to operate without pumps?

Bernoulli's principle: fast-moving water creates low pressure that lifts the boat Hydrostatic pressure: opening sluice gates lets water flow from the higher reservoir into the chamber under gravity until levels equalise Pascal's law: a pump pressurises the chamber to push the boat upward Archimedes' principle: removing water from the chamber increases the boat's buoyancy