Question

A spinning ice skater on extremely smooth ice is able to control the rate at which she rotates by pulling in her arms. Which of the following statements are true about the skater during this process? (There could be more than one correct choice.)

Her kinetic energy remains constant.
Her moment of inertia remains constant.
Her angular momentum remains constant.
She is subject to a constant non-zero torque.

Answer 1

Answer:

Correct -> Her angular momentum remains constant.

Explanation:

If the skater pulls her arms, her radius changes, so her moment of inertia changes.

By definition, moment of inertia is the resistance to rotation. So, if her moment of inertia decreases, her angular velocity increases, because if there is no external torque (in this question there is none), angular momentum is conserved.

$L = I\omega$

$K = \frac{1}{2}I\omega^2$

If the moment of inertia decreases by half, the angular velocity doubles. In that case kinetic energy also increases, because the square of the angular velocity affects the kinetic energy more than the decrease of the moment of inertia.

Answer 2

Statements that are true about the skater during this process is Its Her angular momentum remains constant, and Its moment of inertia remains constant.

What happens when a skater who is spinning with outstretched arms pulls in his arms?

When the skater shrinks her arms and legs, she is bringing her mass closer to the axis of rotation and this leads to a decrease in her moment of inertia. So, if its moment of inertia decreases, its angular velocity increases in order to compensate for equal angular momentum.

With this information, we can conclude that the statements that are true about the skater during this process are Her angular momentum remains constant, and Its moment of inertia remains constant.

Learn more about kinetic in brainly.com/question/999862