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Try this! - Motion of System Of Particles and Rigid Body - NEET

Two rotating bodies A and B of masses m and 2m with moments of inertia IA and I_B \left( {I_B > I_A } \right) have equal kinetic energy of rotation. If LA and LB be their angular momenta respectively, then

  • Option 1)

    L_A = \frac{2}

  • Option 2)

    L_A = 2L_B

  • Option 3)

    L_B > L_A

  • Option 4)

    L_A > L_B

 
Answers (1)
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As we learnt in

Kinetic energy of rotation -

K=frac{1}{2}Iw^{2}

- wherein

I = moment of inertia about axis of rotation

w = angular velocity

 

 I_B>I_A (given)

K=\frac{1}{2}Iw^2

K=\frac{L^2}{2m}

\frac{L^2}{2m}=\frac{1}{2}Iw^2. (use)

So, L_B>L_A


Option 1)

L_A = \frac{2}

Incorrect

Option 2)

L_A = 2L_B

Incorrect

Option 3)

L_B > L_A

Correct

Option 4)

L_A > L_B

Incorrect

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