1. Her angular speed increases because by pulling in her arms she creates a net torque in the direction of rotation. 2. Her angular speed increases because air friction is reduced as her arms come in. 3. Her angular speed increases because her angular momentum is the same but her moment of inertia decreases. 4. Her angular speed increases because her potential energy increases as her arms come in. 5. Her angular speed increases due to a net torque exerted by her surroundings. 6. Her angular speed increases because her angular momentum increases.

3. Her angular speed increases because her angular momentum is the same but her moment of inertia decreases

Explanation:

II ωi the intial angular momentum of the skater. Her angular momentum changes to If ωf after pulling her arms in.

It must be noted that If is less than II, then it is because her arms now go round not far from the rotation axis which brings down the mementos of inertia.

Angular momentum does not change since torque is O.

Note: the mathematical representations are better written on the attached diagram.

this is poiselle's equation from fluid mechanic in physics. mech eng