36. Two discs of moment of inertia

Two discs of moment of inertia I₁ and I₂ and angular speeds ω₁ and ω₂ are rotating along collinear axes passing through their centre of mass and perpendicular to their plane. If the two are made to rotate together along the same axis the rotational KE of system will be

(a)   (I₁ω₁ + I₂ω₂)/2(I₁+I₂)

(b) (I₁+I₂)(ω₁+ω₂)²/2

(c)    (I₁ω₁ + I₂ω₂)²/2(I₁+I₂)

(d)  None of these

Ans. c

(17)