A horizontal disc rotates freely with angular velocity `omega` about a vertical axes through its centre. A rig having the same mass and radius as the disc, is now gently placed coaxially on the disc. After some time, the two rotate with a common angular velocity. then.A. no friction exists between te disc and the ringB. the angular momentum of the system is conservedC. the final common angular velocity is `(1)/(2)omega`D. all of the above

A horizontal disc rotates freely with angular velocity `omega` about a

1.	A horizontal disc rotates freely with angular velocity `omega` about a vertical axes through its centre. A rig having the same mass and radius as the disc, is now gently placed coaxially on the disc. After some time, the two rotate with a common angular velocity. then.A. no friction exists between te disc and the ringB. the angular momentum of the system is conservedC. the final common angular velocity is `(1)/(2)omega`D. all of the above
Answer» `I_(1)omega_(1)=I_(2)omega_(2)` `thereforeomega_(2)=((I_(1))/(I_(2)))omega_(1)=(((1)/(2)mR^(2)))/(((1)/(2)mR^(2)+mR^(2)))omega=(omega)/(3)`

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