Question

the radius of platform is 20cm mass of coin is 20gm and u= 0.4 then find maximum angular speed of the platform so that coin doesn't slip .​

Answer 1

I think ‘u’ here refers to coefficient of friction. So, for the coin doesn’t slip frictional force between the coin and the platform must be equal to the centrifugal force due to rotation. Therefore, umg=m(w^2)r w=angular speed
=>ug=(w^2)r
=>w=(ug/r)^0.5=(0.4*10/0.2)^0.5=20^0.5 rad/s