Question 231 of 280

A bob of mass m attached to an inextensible string of length $l⁡$ is suspended from a vertical support. The bob rotates in a horizontal circle with an angular speed $\omega$ rad/s about the vertical. About the point of suspension :

AAngular momentum is conservedBAngular momentum changes in magnitude but not in directionCAngular momentum changes in direction but not in magnitudeDAngular momentum changes both in direction and magnitude

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Answer: (C) Angular momentum changes in direction but not in magnitude

$\tau =\text{mg}\times l \text{sin} \theta$. (Direction parallel to plane of rotation of particle)



as $\tau$ is perpendicular to $\vec{\text{L}}$, direction of L changes but magnitude remains same.