Who this is for: Cambridge IGCSE Physics (0625) students who want Pressure — using P = F/A, P = ρgh and explaining how area affects pressure — to become a reliable source of marks instead of a formula they apply without picturing the force and surface.
What query it owns: how to understand and revise Pressure in Cambridge IGCSE Physics.
Why this is safe: this page owns the Pressure revision-guide angle, while Tutopiya’s Pressure subtopic page owns the learning resource and the free Pressure quiz owns the practice.

Pressure connects force and area in Cambridge IGCSE Physics (0625) and extends to liquids and gases. Examiners expect you to calculate pressure on surfaces, explain why sharp knives cut more easily, and use P = ρgh for liquid columns. This guide explains both pressure formulas, everyday applications, the question types that actually appear, and where to practise each skill.

Key takeaways

• Pressure P = F/A — unit pascal (Pa) = N/m².
• Larger area → lower pressure for the same force (snow shoes, wide tyres).
• Liquid pressure: P = ρgh — increases with depth; independent of container shape.
• Atmospheric pressure ≈ 10⁵ Pa at sea level; measured with a barometer.

What is Pressure in Cambridge IGCSE Physics?

Pressure is force per unit area acting perpendicular to a surface. For a solid, P = F/A. In a liquid, pressure at depth h depends on density ρ and gravitational field strength: P = ρgh. Cambridge IGCSE questions often ask you to compare pressures, explain applications such as hydraulic systems, or calculate pressure at the bottom of a water column.

You can read the full explanation, worked examples and notes on Tutopiya’s Pressure subtopic page before you attempt questions.

The core ideas you must master

These four ideas appear again and again. Learn what each one means and the exam phrasing that signals it.

Idea	What it means	How the exam uses it
Pressure on solids	P = F/A	”Calculate the pressure on the floor”
Area effect	Same F, smaller A → higher P	”Explain why a sharp knife cuts well”
Liquid pressure	P = ρgh	”Find the pressure at 10 m depth”
Atmospheric pressure	Pressure of the air column	”State the value of atmospheric pressure”

How to calculate pressure — step by step

The safest method works for solid-surface and liquid-depth questions.

1. Identify whether the question involves a solid surface (P = F/A) or a liquid (P = ρgh).
2. Convert units — area in m², depth in m, density in kg/m³.
3. Write the formula and substitute.
4. Give the answer in pascals (Pa) unless kPa is more convenient.
5. For explain questions, link smaller area or greater depth to higher pressure.

Once you have worked through a few, test yourself with the free Pressure quiz — it tells you fast whether the method has actually stuck.

Solid vs liquid pressure: which formula does the question want?

Students lose marks by using P = F/A for liquid depth questions or leaving area in cm².

Situation	What to do	Typical signal words
Object on a surface	P = F/A; F often weight	”block on table”, “pressure on ground”
Sharp vs blunt tool	Smaller contact area → higher P	”knife”, “drawing pin”, “snowshoe”
Depth in liquid	P = ρgh	”under water”, “depth”, “dam wall”
Atmospheric	~10⁵ Pa; barometer	”air pressure”, “mercury barometer”

Pressure in past-paper wording: command words that matter

Most lost marks come from area unit conversion and confusing pressure with force.

Command word / phrase	What the question wants	Typical Pressure stem
Calculate / Work out	P = F/A or P = ρgh	”Work out the pressure at the base of the tank.”
Explain	Link area or depth to pressure	”Explain why caterpillar tracks reduce pressure.”
State	Definition or atmospheric value	”State what is meant by pressure.”
Compare	Two pressures with reasoning	”Compare the pressure under each foot.”
Suggest	Application of pressure ideas	”Suggest why dams are thicker at the base.”

Worked exam-style stems (how to answer the wording)

Practising the wording — not just the formula — is what method marks reward. Here is how three real-style stems are answered.

1. “A force of 200 N acts on an area of 0.5 m². Calculate the pressure.” P = F/A = 200/0.5 = 400 Pa. Mark-scheme reward: formula, division, unit Pa.
2. “Water has density 1000 kg/m³. Calculate the pressure at 3 m depth. Take g = 10 N/kg.” P = ρgh = 1000 × 10 × 3 = 30 000 Pa (or 30 kPa). Reward: all three factors.
3. “Explain why a drawing pin pierces skin more easily than a blunt pencil with the same push.” The pin has much smaller area, so for the same force the pressure is much greater. Reward: both force and area linked.

When you can recognise the wording instantly, work the full set on the Motion, Forces and Energy topical past-paper questions and the Pressure quiz to lock the method in.

How Pressure connects to the rest of Motion, Forces and Energy

Liquid pressure uses density from Density and weight from Mass and Weight. Force ideas from Forces underpin every P = F/A calculation. Gas pressure links forward to the particle model in Kinetic Particle Model of Matter. When you are ready to move on, the Cambridge IGCSE Physics resource hub lets you jump straight from a weak subtopic into the next.

Common mistakes students make

• Leaving area in cm² when calculating Pa (need m²).
• Confusing pressure with force.
• Thinking liquid pressure depends on width of the container — only depth matters.
• Forgetting to use density in kg/m³ in P = ρgh.
• Stating atmospheric pressure without the correct order of magnitude (~10⁵ Pa).

When you need more support

If Pressure questions keep tripping you up — especially unit conversion or explain-style answers — work through the Motion, Forces and Energy topical past-paper questions and the Pressure quiz to pinpoint the exact gap, then get focused help from a Cambridge IGCSE Physics tutor to fix it quickly.

Frequently asked questions

Is Pressure hard in Cambridge IGCSE Physics? The formulas are direct. Marks are lost on unit conversion, confusing force with pressure and weak explanations.

What is a pascal? One pascal equals one newton per square metre (1 Pa = 1 N/m²).

Does pressure in a liquid depend on the shape of the container? No — at a given depth, pressure depends on ρ, g and h only.

How do I revise Pressure effectively? Read the subtopic notes, practise both P = F/A and P = ρgh, then take the Pressure quiz. Revisit any explain questions you got wrong before moving on.

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