Question

A coin placed on a rotating turn table just slips if it is at a distance of 40 cm from the centre if the angular velocity of the turntable is doubled, it will just slip at a distance of

Answer 1

(w= angular velocity)
F= m w^2 r
F slip= m w^2 40. --> eqn(1)
F slip= m (2w)^2 R2
F slip=4m w^2 R2 --> eqn(2)
solving 1 and 2
m w^2 40 = 4 m w^2 R2
so R2 = 10 cm

Answer 2

(w= angular velocity)

F= m w^2 r

F slip= m w^2 40. --> eqn(1)

F slip= m (2w)^2 R2

F slip=4m w^2 R2 --> eqn(2)

solving 1 and 2

m w^2 40 = 4 m w^2 R2

so R2 = 10 cm