A coin is kept a distance of 10 cm from the centre of a circular turntable. If the coefficient of static friction between the table and the coin is 0.8 find the frequency of rotation of the disc at which the coin will just begin to slip.

Explanation

Here, radius, `r=10cm=0.1m, mu_(s)=0.8`
`F=mumg`
`mr omega^(2)=mu mg`
`r omega^(2)=mug`
`omega=(mug)/(r)=sqrt((0.8xx9.8)/(0.1))=sqrt(8xx9.8)`
`=8.854" rad/s"`
`omega=2pi eta`
`therefore` frequency `n=(omega)/(2pi)=(8.854)/(2xx3.14)=1.409rps`
`n=1.409xx60=84.54" rpm"`
84.54 rpm