Question

A circular disc is rotating without friction
about its natural axis with an angular velocity
w. Another circular disc of same material and
thickness but half the radius is gently placed
over it coaxially. The angular velocity of
composite disc will be​

Answer 1

Answer:

Let the mass of bigger disc be M =πR²tρ

let the mass of smaller disc be m

m= π(R/2)²tρ = M/4

by conservation of angular momentum

(MR²/2) ω =(MR²/2)ω1 +(m)(R/2)²ω1

ω1 =16ω/17

hope it help ✌️