Question

A ballet dancer is rotating on smooth horizontal floor with an angular momentum $L$. The dancer folds her hands so that her moment of inertia decreases by $25\%$. The new angular momentum is :

• A. $\frac{3L}{4}$
• B. $\frac{L}{4}$
• C. $\frac{L}{2}$
• D. $L$

Answer 1

Answer: (D)

$L$

Since there is no external torque in action , Angular momentum will remain conserve. When moment of inertia will decrease then angular velocity will increase ,so final angular momentum will be L only.