Circular motion, string, particle, mass, inextensible string, taut, tension, instantaneous, instantaneously, rest.
[STEP III 2018 Question 11 (Mechanics)]
Underground Mathematics: Selected worked STEP questions
STEP Question database
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University of Cambridge Admissions Office: Undergraduate course information for Mathematics
Stephen Siklos' "Advanced Problems in Mathematics" book (external link)
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AMSP (Advanced Maths Support programme): Support for University Admission Tests (external link)