It changes the system's angular momentum.

Their moment of inertia decreases, causing their angular speed to increase while conserving angular momentum.

The angular speed decreases.

The angular momentum remains constant (it is conserved).

It changes the object's angular momentum.

It changes the object's angular momentum.

Their moment of inertia decreases, and their angular speed increases, conserving angular momentum.

The total angular momentum of the system is conserved.

The angular speed increases to conserve total angular momentum.

It changes the object's angular momentum.

Linear Momentum: Associated with translational motion, $\vec{p} = m\vec{v}$. Angular Momentum: Associated with rotational motion, $\vec{L} = I\vec{\omega}$ or $\vec{L} = \vec{r} \times \vec{p}$.

Linear Impulse: Change in linear momentum, $\vec{J} = \int \vec{F} dt = \Delta \vec{p}$. Angular Impulse: Change in angular momentum, $\int \vec{\tau} dt = \Delta \vec{L}$. Both are vector quantities.

Force: A push or pull that causes linear acceleration. Torque: A twisting force that causes angular acceleration.

Mass: Measure of an object's resistance to linear acceleration. Moment of Inertia: Measure of an object's resistance to angular acceleration; depends on mass distribution.

Rotational Kinetic Energy: Kinetic energy due to rotational motion, $KE_{rot} = \frac{1}{2}I\omega^2$. Translational Kinetic Energy: Kinetic energy due to translational motion, $KE_{trans} = \frac{1}{2}mv^2$.