Correct option: (D) n2ω
Explanation:
for solid sphere, MI = (2/5)MR2
angular momentum is always conserved.
L1 = L2
I1ω1 = I2ω2
here ω1 = ω
hence
ω2 = [(I1ω) / I2] (1)
Initial MI = I1 = (2/5)MR12
Radius is reduced to (1/n) of original value hence R2 = (R1 / n) (2)
hence
new MI = I2 = (2/5)MR22
from (1)
ω2 = (ω)[{(2/5)MR12} / {(2/5)MR22}] = (ω)(R1 / R2)2
ω2 = ω ∙ n2 from (2)