1.

Three objects , A : (a solid sphere) , B : (a thin circular disk ) and C : (a circular ring) , each have the same mass M and radius R . They all spin with the same angular speed omega about their own symmetry axes . The amounts of work (W) required to bring them to rest , would satisfy the relation .

Answer»

`W_(C) gt W_(B) gt W_(A)`
`W_(A) gt W_(B) gt W_(C)`
`W_(B) gt W_(A) gt W_(C)`
`W_(A) gt W_(C) gt W_(B)`

Solution :Work done required to bring a OBJECT to rest
`DELTA W = Delta KE`
`Delta W = (1)/(2) I omega^(2)` , where I = MOMENT of inertia
For same `omega , Delta W prop I`
For a solid sphere , `I_(A) = (2)/(5) MR^(2)`
For a THIN CIRCULAR disk , `I_(B) = (1)/(2) MR^(2)`
For a circular ring , `I_(C) = MR^(2)`
`therefore I_(C) gt I_(B) gt I_(A) therefore W_(C) gt W_(B) gt W_(A)`


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