This worked example covers Worked Examples 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 10 of 16 in this topic. Treat this as a marking guide for what examiners are looking for, not just a fact list.
🧮 Worked Examples
Example 1: Finding Pressure (P = F/A)
Calculate the pressure exerted on the floor.
Write the formula: P = F / A
Substitute: P = 600 / 0.030
Answer: P = 20,000 Pa
Example 2: Finding Force (F = P × A)
Calculate the force exerted by the air on the window.
Write the formula: F = P × A
Substitute: F = 101,000 × 2.0
Answer: F = 202,000 N (about 202 kN — this is why windows must be strong!)
Example 3: Pressure in a Liquid — P = hρg (Higher Tier)
Calculate the pressure due to the seawater at that depth.
Write the formula: P = hρg
Substitute: P = 20 × 1025 × 9.8
Answer: P = 200,900 Pa ≈ 201 kPa
Note: total pressure on the diver also includes atmospheric pressure (101 kPa) on top.
Quick Check: Explain why a sharp knife cuts more easily than a blunt knife, even when the same force is applied.
A sharp knife has a much smaller cutting edge area. Using P = F/A, for the same force, a smaller area produces a much greater pressure. The higher pressure is more effective at cutting through the material.
Practice questions for Pressure
What is the correct equation for pressure?
Explain why a sharp knife cuts through food more easily than a blunt knife, even when the same force is applied to both.