Key idea
Pressure in fluids
p = p₀ + ρgh
Start with the central idea, then test it against a concrete element or example. A scientific model is useful when we know what it explains — and where its limits are.
Pressure in fluids
The key idea
Pressure measures normal force per unit area. In a fluid at rest, pressure changes with depth because the fluid above has weight.
Why it matters
This explains why pressure is not simply 'a force': the same force distributed over a different area produces a different pressure.
A picture to remember
Key idea
Pressure in fluids
Guided example
Pressure in fluids
Start with the central idea, then test it against a concrete element or example. A scientific model is useful when we know what it explains — and where its limits are.
Put it into practice
Pressure in fluids
Choose a concrete case linked to Pressure in fluids. Write down the known information, what you are trying to find, and the units. Then state the rule, model or trend you will use. If a calculation is involved, keep the units visible at every line; if it is conceptual, state what changes and what remains fixed.
Check your answer
A strong answer contains four things: the starting situation, the variable that changes, the direction or numerical result, and one check. The check can be a unit, an order of magnitude, a limiting case or a comparison with a familiar example.