A-LevelPhysicsPhysical quantities and units9702/22 · Feb/Mar 2025 · Q17 Marks
Explain what is meant by the accuracy of a measured value.
- (a)Explain what is meant by the accuracy of a measured value.[1]
- (b)Two solid cubes, A and B, are measured to determine the density of their materials. Table 1.1 shows the measurements for cube A. Table 1.1 quantity measurement length of side (1.53±0.01)cm mass (31.3±0.5)g
- (b)(i)Show that the calculated density of the material of cube A is 8.7 × 10³kgm⁻³.[2]
- (b)(ii)Calculate the percentage uncertainty in the density of the material of cube A. percentage uncertainty = ................................................................% [2][2]
- (b)(iii)The density of the material of cube B is determined to be 9.2 × 10³kgm⁻³±6%. State and explain whether cube A and cube B could be made from the same material.[2]
Mark scheme
Marking points from the official mark scheme (Feb/Mar 2025). The mark or mark type is shown in brackets.
- A1 how close the (measured) value is to the true value (of the quantity)
- C1 (p =) m / V
- = 31.3 × 10-3/ (1.53 × 10−2)3 = 8.7 × 103 (kg m-3)
- A1
- C1 (0.5 /31.3) or (0.01 / 1.53)
- % uncertainty = (0.016 × 100) + 3 × (0.0065 × 100)
- A1 = 4%
- M1 The ranges (of the densities of A and B) overlap or the (calculated) density of A is within the range of the density of B or the difference in densities is within the uncertainty (of B)
- A1 (so) they could be the same
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