Materials | OCR A-Level Physics A (H556)
Materials
- 57 questions
- 5 subtopics
- Module 3: Forces and motion
- Paper 1 and Paper 3
How solids deform: Hooke's law and springs, the energy stored in a stretched material, stress, strain and the Young modulus, and what a stress-strain graph reveals about a material..
It covers hooke's law and springs, force-extension graphs and work done, elastic potential energy, stress and strain, the Young modulus and stress-strain graphs and material behaviour.
Sample questions from Materials
Answer each one closed book first, then open the answer.
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Hooke's law and springs
What is the force constant k of a spring or wire?
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The force per unit extension -
Hooke's law and springs
When investigating force-extension characteristics, how should the sample be oriented?
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The sample should be suspended vertically -
Force-extension graphs and work done
State the formula for work done when stretching a material that obeys Hooke's law.
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E = ½Fx, where E is work done (or energy stored), F is force, and x is extension -
Force-extension graphs and work done
Describe two characteristic features of the force-extension behaviour of rubber bands.
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Rubber bands show non-linear force-extension behaviour and exhibit hysteresis when loading and unloading -
Elastic potential energy, stress and strain
Calculate the elastic potential energy when force = 63 N, extension = 0.39 m.
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Elastic potential energy = 0.5 × 63 × 0.39 = 12.3 J. -
Elastic potential energy, stress and strain
Calculate the strain when extension = 0.0064 m, original length = 1 m.
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Strain = 0.0064 ÷ 1 = 0.0064. -
The Young modulus
What are the units of Young modulus and what property of a material does it measure?
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Pascals (Pa); it is a measure of the stiffness of a material -
The Young modulus
How is Young modulus calculated from experimental data?
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From the gradient of the linear region of the stress-strain graph
The 5 subtopics
One subtopic is one session. Work down the list.
| Subtopic | What it covers | Questions |
|---|---|---|
| Hooke's law and springs | Recall questions on tensile and compressive deformation, extension and compression, Hooke's law and the force constant, F = kx calculations, force-extension graphs for springs, investigating force-extension characteristics and elastic deformation. | 17 |
| Force-extension graphs and work done | Recall questions on plotting force-extension graphs, work done from the area under them, E = ½Fx, loading and unloading curves, rubber band behaviour and hysteresis, and a metal wire stretched beyond its elastic limit. | 8 |
| Elastic potential energy, stress and strain | Recall questions on stress and strain with their formulae, units and calculations, elastic potential energy from force and extension or force constant, ultimate tensile strength, the elastic limit and the limit of proportionality. | 14 |
| The Young modulus | Recall questions on defining the Young modulus, its formula, units and calculation, and the experiment to determine it for a wire: measuring length, diameter and extension, why a long thin wire is used, and the graph plotted. | 10 |
| Stress-strain graphs and material behaviour | Recall questions on stress-strain graphs for ductile, brittle and polymeric materials, loading and unloading a polythene strip, and plastic deformation. | 8 |
How the guide is worked
Answering a question from memory stores it far better than reading the answer again. The guide runs that as a fixed procedure on one subtopic at a time, about twenty minutes a session.
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Step 1 · Closed book
Cover the answers. Work through one subtopic and write down what you can. Leave blanks where you have nothing.
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Step 2 · Open book
Go back to the top. Read each printed answer and write it out in full, including the ones you had right.
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Step 3 · Closed book again
Same questions, same order, from memory. The gap between pass one and pass three is the session result.
Read the full method, the return schedule and the research behind it.
Nearby topics
OCR A-Level Physics A Active Recall Guide
Every topic, not just this one. 1,862 questions with their answers.