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55 ideas · 69 connections
Springs and Newton’s second law Density determines upthrust; force balance determines motion Small length errors can matter greatly in density Sample stiffness and Young modulus describe different things Stress and pressure share units, but describe different loading Measuring Young modulus accurately Estimate mass from size and material Materials3.4 Physical quantities2.1.1 Measurements and uncertainty2.2.1 Dynamics3.2.1 Density and pressure3.2.4 Springs3.4.1 Mechanical properties of matter3.4.2
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PHYSICSUK CONNECTIONS
Physics connection

Stress and pressure share units, but describe different loading

OCR A AS Physics · Two ideas, one explanation

Both quantities involve force per area. Naming the force and the area carefully distinguishes tensile stress in a wire from pressure exerted on a surface.

Stress = tensile force / cross-sectional area Pressure = normal force / area

Follow the reasoning

  1. Identify the load and its direction.
  2. Select the area normal to the relevant force.
  3. Express force per area in pascals.
Specification outcomes (2)
  • 3.4.2(c) Define and use stress, strain and ultimate tensile strength.
  • 3.2.4(b) Define pressure; p = F / A for solids, liquids and gases.
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H156 v2.0 · May 2026

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