ForcesDeep Dive

Pressure in Fluids (Liquids and Gases)

Part of Pressure · GCSE GCSE Physics revision

This deep dive covers Pressure in Fluids (Liquids and Gases) within Pressure for GCSE Physics. Revise Pressure in Forces for GCSE Physics with 15 exam-style questions and 12 flashcards. This is a high-frequency topic, so it is worth revising until the explanation feels precise and repeatable. It is section 3 of 16 in this topic. Use this deep dive to connect the idea to the wider topic before moving on to questions and flashcards.

Topic position

Section 3 of 16

Practice

15 questions

Recall

12 flashcards

🌊 Pressure in Fluids (Liquids and Gases)

A fluid is any substance that can flow — this includes both liquids and gases. Pressure in a fluid behaves differently from pressure on a solid surface. There are three key rules:

  • Fluids exert pressure in ALL directions — not just downward. A submarine at depth has water pressing in on it from all sides, not just from above.
  • Pressure increases with depth — the deeper you go, the greater the weight of fluid above you.
  • Pressure at a given depth is the same in all directions at that point.

The formula for pressure due to a column of liquid is:

P = h ρ g
Pressure (Pa) = depth (m) × density (kg/m³) × gravitational field strength (N/kg)

Where h = depth below the surface, ρ (rho) = density of the liquid, and g = 9.8 N/kg on Earth. This is a Higher equation.

Keep building this topic

Read this section alongside the surrounding pages in Pressure. That gives you the full topic sequence instead of a single isolated revision point.

Practice Questions for Pressure

What is the correct equation for pressure?

  • A. Pressure = Force × Area
  • B. Pressure = Force ÷ Area
  • C. Pressure = Area ÷ Force
  • D. Pressure = Force + Area
1 markfoundation

Explain why a sharp knife cuts through food more easily than a blunt knife, even when the same force is applied to both.

3 marksstandard

Quick Recall Flashcards

What is pressure?
The force acting per unit area on a surface. P = F / A
What is the equation for pressure?
P = F / A Pressure (Pa) = Force (N) ÷ Area (m²)

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