Physics 9702 · AS & A Level · Errors and uncertainties

Errors and uncertainties — practice question

A mass is released from rest and travels a distance of $2.0\,\text{m}$ in a vacuum. An observer measures the time for the mass to move through this distance with a stopwatch operated by hand, then repeats the timing twice more. The mean of the three recorded times is used to find a value for the acceleration of free fall, which is calculated as $9.8\,\text{m s}^{-2}$. The measured times are $0.60\,\text{s}$, $0.73\,\text{s}$ and $0.59\,\text{s}$, giving an average of $0.64\,\text{s}$. Which statement is most appropriate for this experiment?

  • AThe measurements are precise and accurate with no evidence of random errors.
  • BThe measurements are not accurate and not always recorded to the degree of precision of the measuring device but the calculated experimental result is accurate.
  • CThe measurements are not always recorded to the degree of precision of the measuring device but are accurate. Systematic errors may be present.
  • DThe range of results shows that there were random errors made but the calculated value is correct so the experiment was successful.

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