Question

most difficult ques in jee from rotation. can anyone solve this​

Answer 1

Answer:

For rotating this circle once the smaller disc will take 10pia/2pia=5 rounds

therefore the C.M.of the assembly rotates about Z-axis with an angular speed of w/5.

Lc=Iew=(1/2ma^2)w+(1/2×4m×(2a)^2)×w=17ma^2w/2

now, Vc=m×wa+4m×2oemga/5m=9wa/5

r perpendicular =ml+4m×2I/5m×9I/5

Lz=81mwa^2underroot24/5×costitha