Cambridge International AS & A Level · 1 · structured
Read measurements and judge their quality
Read measurements and judge their quality · Original GioPhysics question with a detailed, mark-by-mark answer guide.
- Demand
- demanding
- Marks
- 11
- Topics
- 3
- Answer
- Complete
Use SI conventions. Two instruments repeatedly measure a reference length of 50.00 mm. Instrument A reads 52.00, 52.01, 51.99 mm; B reads 49.7, 50.3, 50.0 mm. All values below are illustrative data.
- (a)
Explain what the statement L=0.250 m means by separating numerical magnitude from unit. Express the same length in centimetres and explain what does and does not change.
3 marks - (b)
Give the SI base unit name and symbol for mass, length, time, electric current and thermodynamic temperature.
5 marks - (c)
Which instrument is more precise? Which mean is more accurate? Explain why the answers differ.
3 marks
Ready to self-mark?Reveal the detailed answer guide
(a)
Explain what the statement L=0.250 m means by separating numerical magnitude from unit. Express the same length in centimetres and explain what does and does not change.
Identify what the question is testing, organise the response into distinct mark-earning points, and make every conclusion traceable to a physical principle or to the evidence supplied.
- 1
A physical quantity comprises a numerical magnitude and a unit.
- 2
Multiply 0.250m by 100 cm/m to obtain 25.0 cm.
- 3
The two notations refer to the same length.
(b)
Give the SI base unit name and symbol for mass, length, time, electric current and thermodynamic temperature.
Identify what the question is testing, organise the response into distinct mark-earning points, and make every conclusion traceable to a physical principle or to the evidence supplied.
- 1
Associate each requested quantity with the matching unit and correct case-sensitive symbol.
- 2
Mass uses kg, not g; temperature uses K, not °K.
(c)
Which instrument is more precise? Which mean is more accurate? Explain why the answers differ.
Identify what the question is testing, organise the response into distinct mark-earning points, and make every conclusion traceable to a physical principle or to the evidence supplied.
- 1
A range 0.02 mm is much smaller than B range 0.6 mm.
- 2
A mean 52.00 mm is 2.00 mm from reference, while B mean is 50.0 mm.
- 3
Precision concerns agreement of repeated readings; accuracy concerns closeness to the reference.
Complete marking guidance
Use these worked steps alongside the part-by-part answers. They explain the method and mark allocation; they do not add extra marks.
- (a) A physical quantity comprises a numerical magnitude and a unit.
- (a) Multiply 0.250m by 100 cm/m to obtain 25.0 cm.
- (a) The two notations refer to the same length.
- (b) Associate each requested quantity with the matching unit and correct case-sensitive symbol.
- (b) Mass uses kg, not g; temperature uses K, not °K.
- (c) A range 0.02 mm is much smaller than B range 0.6 mm.
- (c) A mean 52.00 mm is 2.00 mm from reference, while B mean is 50.0 mm.
- (c) Precision concerns agreement of repeated readings; accuracy concerns closeness to the reference.
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