2025 · Paper 2 · Physics
Question 3
The printed question, the official key, and each model’s JSON answer plus the reasoning it wrote.
PhysicsPaper 2Single correct
Q03
Official C
Model answers
Claude Fable 5.1
Anthropic
Correct3 / 3
C
Claude Fable 5.1 reasoning
Rod hinged at O, moment of inertia I = ml²/3. **Fig. 1:** Springs at midpoint (distance l/2) and top (distance l). For small angular displacement θ, restoring torque: τ₁ = k(l/2·θ)(l/2) + k(lθ)(l) = kl²θ(1/4 + 1) = (5/4)kl²θ So ω₁² = (5/4)kl²/I. **Fig. 2:** Both springs at midpoint (distance l/2): τ₂ = 2k(l/2·θ)(l/2) = (1/2)kl²θ So ω₂² = (1/2)kl²/I. Ratio: f₁/f₂ = √[(5/4)/(1/2)] = √(5/2) **Answer: (C)**
GPT 6 Astra
OpenAI
Correct3 / 3
C
GPT 6 Astra reasoning
No written reasoning was returned for this item.
GPT 5.6 Luna
OpenAI
Correct3 / 3
C
GPT 5.6 Luna reasoning
No written reasoning was returned for this item.