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 if

Options

A. `r =mugomega^(2)`
B. `r lt(omega^(2))/(mug)`
C. `rlt(mug)/(omega^(2)`
D. `r ge(mug)/(omega^(2))`

Answer

c

Explanation

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))` .