Rotational Motion

JEE Main level, single correct, medium

235 of 280

Question 235 of 280

This question has Statement 1 and Statement 2. Of the four choices given after the Statements, choose the one that best describes the two Statements.
Statement 1: When moment of inertia
II of a body rotating about an axis with angular speed ω\omega increases, its angular momentum LL is unchanged but the kinetic energy KK increases if there is no torque applied on it.
Statement 2:
L=IωL=I \omega, kinetic energy of rotation =12Iω2=\frac{1}{2} I \omega^2

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Answer: (B) Statement 1 is false, Statement 2 is true.

As L=IωL=I \omega so LL increases with increase in ω\omega. Kinetic energy (rotational) _{\text {(rotational) }} depends on an angular velocity ' ω\omega ' and moment of inertia of the body II.
i.e.,
K⋅E⋅(K \cdot E \cdot\left(\right. rotational =12Iω2=\frac{1}{2} I \omega^2

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