Physics 9702 · AS & A Level · Errors and uncertainties

Errors and uncertainties — practice question

How much uncertainty there is in the momentum of a trolley moving between points X and Y depends on which measuring devices are chosen. Readings for the same trolley taken with different instruments are given below. 1 distance between X and Y measured with a metre rule with cm divisions $= 0.55\,\text{m}$ 2 distance between X and Y measured with a metre rule with mm divisions $= 0.547\,\text{m}$ 3 timings taken with a wristwatch reading to the nearest $0.5\,\text{s}$ at X $= 0.0\,\text{s}$ and at Y $= 4.5\,\text{s}$ 4 timings taken with light gates reading to the nearest $0.1\,\text{s}$ at X $= 0.0\,\text{s}$ and at Y $= 4.3\,\text{s}$ 5 mass of trolley measured with a balance reading to the nearest g $= 6.4 \times 10^{-2}\,\text{kg}$ 6 mass of trolley measured with a balance reading to the nearest $10\,\text{g} = 6 \times 10^{-2}\,\text{kg}$ Which measurements, one for each quantity measured, produce the smallest uncertainty in the trolley's momentum value?

  • A1, 3 and 6
  • B1, 4 and 6
  • C2, 3 and 6
  • D2, 4 and 5

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