2019 Laws of MotionDynamics of Uniform Circular Motion – Vertical Circle Medium Question 21 of 72 in Laws of Motion

A mass $m$ is attached to a thin wire and whirled in a vertical circle. The wire is most likely to break when:

A the mass is at the highest point
B the wire is horizontal
C the mass is at the lowest point
D inclined at an angle of $60^\circ$ from vertical

The answer is C.

Solution

At the lowest point: $T-mg=\frac{mu^2}{l}\Rightarrow T=mg+\frac{mu^2}{l}$ Both weight and speed contribute maximally to tension at the lowest point, so the tension is maximum there and the wire is most likely to break when the mass is at the lowest point.

Concept point of maximum tension in a vertical circle

Laws of Motion in past papers

72 questions from this chapter have appeared across 27 exam years.