Conservation of Angular Momentum:

Since angular momentum is a conserved quantity, if you decrease the moment of inertia, you increase the angular velocity.

Play with the snowman applet to gain further insight.

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As you decreased the length of the snowman's arms, you also decreased the snowman's moment of inertia.

Consequently, the body rotates faster; it has a shorter period. As you progress through this site, you will learn how the conservation of momentum applies to the rapid rotational speeds of pulsars.

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