A Levels Physics (9702)•9702/11/M/J/18

Explanation
Uncertainty propagation for volume of a cube
Steps:
- Volume formula: V = s³, where s = 30.0 mm.
- Relative uncertainty in s: (0.1 / 30.0) × 100% = 0.333%.
- For V = s³, relative uncertainty in V is 3 × relative uncertainty in s = 3 × 0.333% = 1%.
- Percentage uncertainty in volume is 1%.
Why C is correct:
- Relative uncertainty for V = s^n follows δV/V = n × (δs/s); here n=3, so 3 × (0.1/30) × 100% = 1%.
Why the others are wrong:
- A: Equals side's percentage uncertainty, ignoring multiplication by 3.
- B: Approximates side's percentage uncertainty (0.333% ≈ 0.3%) but omits factor of 3.
- D: Overestimates by using absolute uncertainty (0.1 mm) directly or misapplying the factor.
Final answer: C
Topic: Errors and uncertainties
Practice more A Levels Physics (9702) questions on mMCQ.me