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.

The total angular momentum of a closed system remains constant unless acted upon by an external torque.

Angular impulse is the product of the net torque and the time interval over which it acts. Units are $\text{kg} \cdot \text{m}^2/\text{s}$.

A measure of an object's resistance to changes in its rotation rate. It depends on the mass distribution of the object and the axis of rotation.

A system where no external torques act upon it, allowing angular momentum to be conserved.

The rotational equivalent of linear momentum. For a point particle, it is given by $\vec{L} = \vec{r} \times \vec{p}$, where $\vec{r}$ is the position vector and $\vec{p}$ is the linear momentum.

The rotational equivalent of linear momentum. It's conserved in a closed system unless acted upon by an external torque.

The total angular momentum of a closed system remains constant if no external torque acts on it.

A torque applied from outside the system that can change the system's total angular momentum.

The product of the net torque and the time interval over which it acts. Units are $\text{kg} \cdot \text{m}^2/\text{s}$.

A measure of an object's resistance to changes in its rotational motion. Analogous to mass in linear motion.