Edexcel A Level Physics
Edexcel A Level Physics Topic 4: Materials Exam Questions
Free Edexcel A Level Physics exam questions for Topic 4: Materials, with a mark scheme for every pack. Covers density, upthrust, viscosity, Stokes' law, laminar and turbulent flow, Hooke's law, stress, strain, Young modulus and elastic strain energy.
Topic 4: Materials exam questions
2 question packs of real past exam questions, each with its mark scheme. Do not stop after a few: answer as many as you can without notes, then mark every answer with the mark scheme. The more questions you do, the more quickly you will spot how examiners ask about each idea.
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A-Level Physics Flashcards for 2027 Onwards
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About Edexcel A Level Physics Topic 4: Materials
Topic 4: Materials in Edexcel A Level Physics has two parts: fluids and solids. In fluids you work with density, upthrust and Archimedes' principle, viscous drag and Stokes' law, and the difference between laminar and turbulent flow. In solids you use Hooke's law, stress, strain and the Young modulus, and interpret force-extension and stress-strain graphs. Two core practicals belong here: the falling ball method for viscosity and determining the Young modulus of a material. It is assessed in Paper 2: Advanced Physics II. Examiners often ask about the conditions for Stokes' law and how temperature affects viscosity.
What you need to know
- Density and upthrust ρ = m/V. Upthrust equals the weight of fluid displaced (Archimedes' principle).
- Viscosity and Stokes' law Viscous drag on a small sphere moving slowly through a fluid with laminar flow is F = 6πηrv. Viscosity of liquids decreases as temperature increases.
- Laminar and turbulent flow In laminar flow, layers move smoothly with no mixing; in turbulent flow, there are eddies and mixing. Stokes' law only applies for laminar flow.
- Hooke's law ΔF = kΔx up to the limit of proportionality. Elastic strain energy ΔEel = ½FΔx, the area under the force-extension graph.
- Stress, strain and Young modulus Stress = F/A, strain = Δx/x, E = stress/strain. Know elastic and plastic deformation, yield point, breaking stress and properties such as stiffness, brittleness and ductility.
Common mistakes in Topic 4: Materials
- Using the density of the object, not the fluid, for upthrust.
- Applying Stokes' law to large or fast objects where flow is turbulent.
- Saying the viscosity of a liquid increases with temperature. It decreases.
- Using the diameter as the radius in Stokes' law or stress calculations.
- Giving the Young modulus as the gradient of a force-extension graph. It is the gradient of the stress-strain graph in the linear region.
Try three Topic 4: Materials exam-style questions
1. A sphere of radius 2.0 mm falls at 0.050 m s^-1 through oil of viscosity 1.5 Pa s. Calculate the viscous drag. (2 marks)
Show the mark scheme answer
F = 6πηrv = 6π × 1.5 × 2.0 × 10^-3 × 0.050; F = 2.8 × 10^-3 N.
2. A block of volume 2.0 × 10^-4 m^3 is fully submerged in water of density 1000 kg m^-3. Calculate the upthrust. (2 marks)
Show the mark scheme answer
Weight of water displaced = ρVg = 1000 × 2.0 × 10^-4 × 9.81; upthrust = 1.96 N.
3. Describe how the falling ball method is used to determine the viscosity of a liquid. (4 marks)
Show the mark scheme answer
Drop a small ball bearing of measured radius into a tall tube of liquid; use marks (or light gates or video) well below the surface so terminal velocity has been reached; measure time to fall a known distance to find v; at terminal velocity weight = upthrust + drag, so use F = 6πηrv to calculate η; repeat and average.
Topic 4: Materials FAQs
What does Edexcel A Level Physics Topic 4: Materials cover?
It covers density, upthrust, viscosity, Stokes' law, laminar and turbulent flow, Hooke's law, elastic strain energy, stress, strain and the Young modulus.
Which paper is Topic 4: Materials examined in?
It is assessed in Paper 2: Advanced Physics II, and like every topic it can also appear in Paper 3: General and Practical Principles in Physics.
Which core practicals are in Materials?
Using a falling ball method to determine the viscosity of a liquid, and determining the Young modulus of a material.
