Physics 9702 · AS & A Level · Errors and uncertainties

Errors and uncertainties — practice question

A student is trying to determine the density $\rho$ of aluminium by measuring a rectangular sheet. mass $m = 51.6 \pm 0.1\,\text{g}$ length $l = 100.0 \pm 0.1\,\text{cm}$ width $w = 10.0 \pm 0.1\,\text{cm}$ thickness $t = 0.20 \pm 0.01\,\text{mm}$ He applies the equation $\rho = \frac{m}{wlt}$ to calculate the density. What is the density value obtained, together with its uncertainty?

  • A$0.26 \pm 0.01\,\text{g cm}^{-3}$
  • B$0.26 \pm 0.02\,\text{g cm}^{-3}$
  • C$2.6 \pm 0.1\,\text{g cm}^{-3}$
  • D$2.6 \pm 0.2\,\text{g cm}^{-3}$

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