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There is a disc of mass M and radius R. ...

There is a disc of mass `M` and radius `R`. A pont charge `+Q` and of mass `m` is fixed at the centre of the disc. The disc is held on a fixed horizontal rough suface . Another point charged `+q` is fixed on the surface such that disance between `+q` and `+Q` is `(4R)/3`. Now the disc is set free. If the disc does not loose contact with the ground at the same intent the relation must hold is `Mgt eta m`. Find `eta`. (Use `(27Qq)/(256pi epsilon_(0)R^(2))=3mg`)

Text Solution

Verified by Experts

The correct Answer is:
2
`(M+m)g gt F_(E)sintheta`
`gt( 27Qq)/(256piepsilon_(0)R^(2))`
`(M+m)g gt 3mg`
`Mgt2mrarreta=2`
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