Question 350: Centre of Mass and Rotational Motion

Question

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:

Accepted Answer

Torque working on the bob of mass $$m$$ is, $$	au  = mg 	imes \ell \,\sin \,	heta .$$ (Direction of torque by the weight is parallel to plane of rotation of the particle)
As $$	au $$ is perpendicular to  the angular momentum $$\overrightarrow L$$ of the bob,  so the direction of $$L$$ changes but magnitude remains same.

Answer

angular momentum is conserved

Answer

angular momentum changes in magnitude but not in direction.

Answer

angular momentum changes in direction but not in magnitude.

Answer

angular momentum changes both in direction and magnitude.

Centre of Mass and Rotational Motion

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:

Choose the correct answer: