conservation of angular momentum

Question

Figure skater pulls arms inward reducing I to half. ω becomes:

RankGuru · Accepted Answer

According to the Law of Conservation of Angular Momentum, if the net external torque is zero:
$L_{initial} = L_{final} \implies I_1 \omega_1 = I_2 \omega_2$
Given:
- $I_2 = \frac{1}{2} I_1$
Substituting:
$I_1 \omega_1 = (\frac{1}{2} I_1) \omega_2$
$\omega_2 = 2 \omega_1$
The angular speed **doubles**. This explains why skaters spin much faster when they pull their limbs toward their axis of rotation.

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