2025 · Paper 1 · Physics
Question 13
The printed question, the official key, and each model’s JSON answer plus the reasoning it wrote.
PhysicsPaper 1Numerical
Q13
Official 72
Model answers
Claude Fable 5.1
Anthropic
Correct4 / 4
72
Claude Fable 5.1 reasoning
Electron in n = 3 orbit: 2πr = nλ, with r = n²a₀/Z, so λ = 2πr/n = 2π n a₀/Z = 6πa₀/Z. Neutron: λ = h/√(2 m_N k_B T) ⇒ k_B T = h²/(2 m_N λ²) = h² Z²/(2 m_N · 36π² a₀²) = Z²h²/(72 π² a₀² m_N k_B)·k_B. So T = Z²h²/(72 π² a₀² m_N k_B), giving α = 72.
GPT 6 Astra
OpenAI
Correct4 / 4
72
GPT 6 Astra reasoning
No written reasoning was returned for this item.
GPT 5.6 Luna
OpenAI
Correct4 / 4
72
GPT 5.6 Luna reasoning
No written reasoning was returned for this item.