A horizontal disc of diameter 10 cm is spinning freely about a vertical axis
through its centre at an angular speed of 80 revolutions per minute. A piece
of putty of mass 7.0 g drops on to and sticks to the disc a distance of 3.0 cm
from the centre. The angular speed reduces to 65 revolutions per minute.
Calculate the moment of inertia of the disc.
The Attempt at a Solution
but if i use the formula I= MR2,,,, what about the informaton they have given of rev/ min this is the angular speed....
not sure the method to do this???