PHYSICS CONNECTION
Measuring Young modulus accurately
A thin wire’s diameter is measured to calculate its cross-sectional area. The squared diameter makes this measurement especially important in a Young-modulus calculation.
E = FL/(Ax) A = πd²/4
Follow the reasoning
- Measure diameter at several positions and orientations.
- Measure extension from the original length, correcting any zero offset.
- Combine uncertainties with the correct powers.
OFFICIAL OCR QUESTIONS
Try it in a past paper 1
Open the question, then use its mark scheme to check your work.
Question 21(b)–(c)
Determine Young modulus and evaluate measurement uncertainty.
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ORIGINAL PHYSICSUK QUESTIONS
Put the ideas to work
More practice is on its way
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Specification outcomes (4)
- 3.4.2(d)(i) Define Young modulus, E = stress / strain.
- 3.4.2(d)(ii) Use techniques and procedures to determine the Young modulus for a metal.
- 2.2.1(a) Understand systematic errors (including zero errors) and random errors in measurements.
- 2.2.1(c) Calculate absolute and percentage uncertainties when data are combined by addition, subtraction, multiplication, division or raising to powers.