Question

What happen when you place a coin on a circular rotating disc

Answer 1

It will slip at a distance of 4 cm. When angular velocity is doubled, centrifugal force becomes four times because centrifugal force is proportional to square of angular velocity. To keep the centrifugal force same on the coin, the radial distance will have to be reduced to 1/4 of original distance i.e 1/4 x 16 = 4 cm.

Answer 2

if the rotating disc is with less than 1000 rpm speed then the coin will be stablised on the disc or if the speed is very more than that the coin may get struck off .