2025 · Paper 2 · Physics
Question 9
The printed question, the official key, and each model’s JSON answer plus the reasoning it wrote.
PhysicsPaper 2Numerical
Q09
Official 1.65 – 1.67
Model answers
Claude Fable 5.1
Anthropic
Correct4 / 4
1.67
Claude Fable 5.1 reasoning
Conducting sphere: charge on surface (spherical shell), mass distributed in solid sphere. Magnetic moment of rotating charged shell: μ = (1/3) Q ω R². Angular momentum of solid sphere: L = (2/5) M R² ω. Ratio μ/L = (1/3)/(2/5) · Q/M = (5/6) Q/M = (5/3) · Q/(2M). So α = 5/3 ≈ 1.67.
GPT 6 Astra
OpenAI
Correct4 / 4
1.67
GPT 6 Astra reasoning
No written reasoning was returned for this item.
GPT 5.6 Luna
OpenAI
Correct4 / 4
1.67
GPT 5.6 Luna reasoning
No written reasoning was returned for this item.