A gramphone record is revolving with an angular velocity `omega`. A coin is placed at a distance `R` from the centre of the record. The static coefficient of friction is `mu`. The coin will revolve with the record ifA. `r =mugomega^(2)`B. `r lt(omega^(2))/(mug)`C. `rlt(mug)/(omega^(2)`D. `r ge(mug)/(omega^(2))`

A gramphone record is revolving with an angular velocity `omega`. A co

1.	A gramphone record is revolving with an angular velocity `omega`. A coin is placed at a distance `R` from the centre of the record. The static coefficient of friction is `mu`. The coin will revolve with the record ifA. `r =mugomega^(2)`B. `r lt(omega^(2))/(mug)`C. `rlt(mug)/(omega^(2)`D. `r ge(mug)/(omega^(2))`
Answer» Correct Answer - c The coin will revolve with the record if centrifugal force `MR omega^(2) lt f` (force of friction) `mr omega^(2) lt muR` or `mromega^(2) lt mu mg` `r lt (mug)/(omega^(2))` .

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