These eight original questions cover the four lessons in SPM Physics measurement. Write full working before opening each answer.
Questions
Question 1. Convert 0.85 km to m and 620 µm to m.
Answer
0.85 km = 0.85 × 10³ = 850 m.
620 µm = 620 × 10⁻⁶ = 6.2 × 10⁻⁴ m, which is 0.00062 m.
Question 2. Convert 3.0 cm² to m² and 250 cm³ to m³.
Answer
3.0 cm² = 3.0 × 10⁻⁴ m² = 0.00030 m².
250 cm³ = 250 × 10⁻⁶ m³ = 2.5 × 10⁻⁴ m³.
See converting SI prefixes and units for the squared and cubed factors.
Question 3. Convert 54 km/h to m/s.
Answer
54 × 1 000 ÷ 3 600 = 54 ÷ 3.6 = 15 m/s.
Question 4. Classify each as scalar or vector: mass, acceleration, time, displacement, speed.
Answer
Scalar: mass, time, speed. Vector: acceleration, displacement.
Use the direction test: a scalar is complete without a direction. See scalar and vector quantities.
Question 5. A cyclist rides 9 km west and then 12 km south. Find the distance and the size of the displacement.
Answer
Distance = 9 + 12 = 21 km.
Displacement = √(9² + 12²) = √225 = 15 km, at tan⁻¹(12 ÷ 9) = 53° south of west.
Question 6. A vernier caliper reads 3.4 cm on the main scale, and the 7th vernier mark aligns. The zero error is +0.02 cm. Find the corrected reading.
Answer
Observed = 3.4 + 7 × 0.01 = 3.47 cm.
Corrected = 3.47 − 0.02 = 3.45 cm. A positive zero error means the instrument reads high, so subtract it.
Question 7. A micrometer reads 4.5 mm on the sleeve and 18 on the thimble. Its zero error is −0.04 mm. Find the corrected reading.
Answer
Observed = 4.5 + 18 × 0.01 = 4.68 mm.
Corrected = 4.68 − (−0.04) = 4.72 mm. A negative zero error means the instrument reads low, so add its size.
Question 8. You must plot potential difference from 0 V to 6.0 V on a vertical axis 20 cm tall. Suggest a scale and give one way of making the graph unsuitable.
Answer
A scale of 2 cm for 1.0 V uses 12 cm for 6.0 V. A scale of 3 cm for 1.0 V would use 18 cm and also fits, but 2 cm per volt is easier to read.
A graph would be unsuitable if the scale were 1 cm for 3 V, which squeezes all the points into 2 cm of the 20 cm axis, or if the axis label had no unit.
If you got these wrong
For Questions 1 to 3, go back to converting SI prefixes and units. Question 8 links to plotting a graph with appropriate scale and units.
The timed original practice session builder can turn this set into a timed session. For a teacher to work through the questions you missed, see online one-to-one Physics tuition.