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Edexcel A-Level Physics A2 Combined Measurement Uncertainty

Edexcel A-Level Physics A2 Combined Measurement Uncertainty
Pearson Edexcel International Advanced Subsidiary/Advanced Level in Physics, Issue 3, July 2021Physics XPH11/YPH11

Review combined measurement uncertainty in Edexcel A-Level Physics through subtracted readings, powered terms, percentage uncertainty and range comparisons.

How this is tested

  • add absolute uncertainties for subtracted readings before converting the result to percentage uncertainty
  • double a percentage uncertainty for squared terms before adding the remaining percentage uncertainties
  • use upper and lower limits from combined uncertainty to support a valid physical conclusion

Question 4(b)(i)

[Maximum number: 3]

A student measured a metal ring of the type shown below.

Figure for Question 4(b)(i) — Edexcel A-Level Physics A2

The student was given a metal ring of a different size. She measured the distances shown.

Figure for Question 4(b)(i) — Edexcel A-Level Physics A2

She calculated the shaded area A of the metal using the formula

A=π4(s2−d2)A=\frac{\pi}{4}\left(s^{2}-d^{2}\right)

Show that the uncertainty in d2d^{2} is about 1 mm21 \mathrm{~mm}^{2}.

d=10.70 mm±0.06 mmd=10.70 \mathrm{~mm} \pm 0.06 \mathrm{~mm}