Two discs of moment of inertia ' I₁ ' and ' I₂ ' and angular speeds '… | MHT CET 2025 (25 Apr, Shift 1)

Q20MHT CET 2025 · 25 APR · SHIFT 1Medium

Angular Momentum & its Conservation

Two discs of moment of inertia ' $I_1$ ' and ' $I_2$ ' and angular speeds ' $\omega_1$ ' and ' $\omega_2$ ' are rotating along the collinear axes passing through their centre of mass and perpendicular to their plane. If the two discs are made to rotate together along the same axis. The rotational kinetic energy of the system will be

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Answer: (d)

Angular momentum conserved: $(I_1+I_2)\omega=I_1\omega_1+I_2\omega_2$ (same sense of rotation).
$K=\frac12(I_1+I_2)\omega^2=\frac{(I_1\omega_1+I_2\omega_2)^2}{2(I_1+I_2)}$
So the answer is (d).

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Angular Momentum & its Conservation question from MHT CET 2025 (25 Apr, Shift 1)

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