ASTR 420 Problem Set 04 Solutions: Nucleosynthesis and Inflation

Instructor solution key

Rubric

Problems 1-4 are 25 points each. Require dimensional consistency, correct comparative direction, explicit assumptions, reproducibility, and interpretation. Accept equivalent derivations when the physical meaning is preserved.

Problem 1

Solution route: define the measured quantity, write the model, substitute shared values, and test the stated assumption.

Key check: With n/p=1/7, Y_p = 2(n/p)/(1+n/p) = 0.25.

Problem 2

Solution route: define the measured quantity, write the model, substitute shared values, and test the stated assumption.

Key check: The analysis must contain a labeled data display, uncertainty or sensitivity treatment, and a provenance statement; an unsupported scalar answer is incomplete.

Problem 3

Solution route: define the measured quantity, write the model, substitute shared values, and test the stated assumption.

Key check: The analysis must contain a labeled data display, uncertainty or sensitivity treatment, and a provenance statement; an unsupported scalar answer is incomplete.

Problem 4

Solution route: define the measured quantity, write the model, substitute shared values, and test the stated assumption.

Key check: The analysis must contain a labeled data display, uncertainty or sensitivity treatment, and a provenance statement; an unsupported scalar answer is incomplete.

Common errors