Deep Water Presses

Why it matters

Dive to the pool floor and your ears complain. They're reporting physics: every metre down, the water above you weighs more.

The idea in plain words

The rules of liquid pressure. Tap them.

deeper → more pressure

Why does the municipal water tank sit on a tall tower?

The tower converts height into water pressure — no pump needed at your sink

• rule 1: depth rule — pressure increases with depth below the surface
• rule 2: all directions — at one depth, a liquid presses equally every way — even upward
• where it shows: applications — dam walls thicker at the base; divers' limits; water towers giving taps their push
• Height above your tap = depth of your tap below the surface
• More height, more pressure at the tap

Predict first

Three holes in a bottle — top, middle, bottom. The strongest jet comes from…

Pressure grows with depth — the bottom hole has the most water pressing above it and fires farthest.

• the bottom hole — correct
• the top hole
• all equal

What you do

Predict the winning hole, then raise the water level and watch every jet obey the depth rule.

Check yourself

Dam walls are thickest at the bottom because…

The deepest water pushes hardest — the concrete profile is a graph of pressure vs depth.

Liquid pressure at a point depends on…

A narrow 10 m pipe presses as hard as a 10 m lake — only h and ρ matter.

A diver 10 m down feels pressure from…

That all-round squeeze is also why the upward part exists — the seed of buoyancy.

• water pressure is greatest at the greatest depth — correct
• the wall must carry its own weight
• waves hit the bottom hardest
• the depth and the liquid's density — correct
• the width of the container
• the total amount of liquid
• all sides — water presses in every direction — correct
• above only
• below only