1.

Two bodies with moments of inertia I1 and I2 (I1 > I2) rotate with the same angular momentum. If E1 and E2 are their rotational kinetic energies, then(A) E2 > E1 (B) E2 = E1(C) E2 < E1(D) E2 ≤ E1

Answer»

Correct option is (A) \(E_2 > E_1\)

Angular Momentum                     \(L = I \omega\)

Given,

\(I_1 = I_2\)

\(I_1 \omega_1 = I_2 \omega_2\)

\(\frac{\omega_1}{\omega_2} = \frac{I_2}{I_1}\)

Kinetic Energy    K.E = \(\frac{1}{2} I\omega^2\)

\(\frac{E_1}{E_2} = \frac{I_1}{I_2} (\frac{\omega_1}{\omega_2})^2\)

\(\frac{E_1}{E_2} = (\frac{I_1}{I_2}) (\frac{\omega_1}{\omega_2})^2\)

\(\frac{E_1}{E_2} = \frac{I_1}{I_2} \times \frac{I_2{^2}}{I_1{}^2}\)

\(\frac{E_1}{E_2} = \frac{I_2}{I_1}\)

Given, \(I_1 > I_2\)

then,

\(E_2 > E_1\)

Correct option is (A) E2 > E1 



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