A coin placed on a rotating turntable just slips if it is placed at a distance of 4 cm from the centre. If the angular velocity of the turntable is doubled, it will just slip at a distance of

Options

A. 27 cm
B. 9 cm
C. 3 cm
D. 1 cm

Answer

D

Explanation

Necessary centripetal force to the coin is provided by friction. Thus, `mromega_(max)^(2)=mumg" or "r=(mug)/(omega_(max)^(2))`
`omega_(max)` is made three times. Therefore, distance from centre r will remain `(1)/(9)` times that is 1 cm.