Long answer·Standard multi-step (3/5)·No calculator
Difficulty guide
The label describes the problem, not your ability.
1/5 - Foundational
Warm-up setup; checks one basic idea.
2/5 - Routine exam skill
Normal syllabus skill; usually one main rule or interpretation.
3/5 - Standard multi-step
Exam-style problem with multiple steps or a common trap.
4/5 - Hard exam skill
High-end exam problem; combines methods carefully.
5/5 - Challenge
Stretch problem beyond normal exam pressure.
Question
Two planets move in nearly circular orbits around the same star. Planet 1 has orbital radius and period . Planet 2 has orbital radius .
Total: 3 marks
(a) Find the period of planet 2 in terms of . (1 mark)
(b) Find the ratio of orbital speeds . (1 mark)
(c) State why the same central star condition matters. (1 mark)
Something wrong with this item?