Case study·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
A liquid flows through a glass tube. As the speed increases beyond a certain value, the flow changes from orderly layers to irregular motion. The Reynolds number helps predict this change.
Total: 4 marks
(a) Name the orderly type of flow. (1 mark)
(b) How does critical speed change if viscosity increases? (1 mark)
(c) How does critical speed change if tube radius increases? (1 mark)
(d) Why is density relevant to the transition? (1 mark)
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