← Back to Training
MCQAdvancedAstrophysical Processes & Nuclear Physics2 parts
USAAAO — 2025 First Round
Questions 2–3
This question has 2 parts that build on each other. Answer both — it only counts as correct if every part is right.
Part AQuestion 2
Suppose a spherical gas giant has radius R, temperature T, uniform density and composition, and fixed volumetric heat capacity. Assuming heat leaves solely through blackbody radiation, calculate how the planet’s cooling rate −dT/dt depends on R, T.
Part BQuestion 3
Let T(t) be the temperature of the planet after time t and let T₀ be the temperature at time t = 0. Calculate the dependence of T/T₀ on t assuming Tenv = 0 is the temperature of the planet’s environment. Below, α is a constant.
Sign in to save your progress.
Answer both parts to check. Both must be correct to count as correct.
Source
USAAAO 2025 First Round, Question 2. Question text, choices, and answer were transcribed from the official USAAAO exam and solutions PDFs.