Spinning on Ice
Performed by every professional figure skater, the objective of the spin is to hold a specific body position while rotating around a single point on the ice.
News You Can Use
 A spin is accomplished by the skater rotating on the part of the blade that is just behind the toe pick. Skaters can perform different types of spins depending on the position of the skater's arms, legs, and body. Spins fall into three different categories: upright spins, sit spins and camel spins. As a skater spins, it can be observed that the rotation speed of the skater generally increases as an outstretched limb is brought closer. This is a result of the conservation of angular momentum.
 Angular momentum is nearly identical to ordinary translational momentum \begin{align*}p\end{align*}
p , except it deals with velocities that are defined in rotational terms. Angular momentum is defined as:
\begin{align*}\overrightarrow{L} = \overrightarrow{r} \times \overrightarrow{p} = rmv \sin \theta\end{align*}
In the above equation, \begin{align*}\overrightarrow{L}\end{align*}

As with translational momentum, angular momentum must be conserved as shown in the following equation.
\begin{align*}\Delta L&= L_{final}  L_{initial}=0 \\
\rightarrow L_{final} &= L_{initial}\end{align*}
So when an ice skater who is spinning with a given angular velocity, \begin{align*}\omega\end{align*}
 Learn more about angular momentum below:
http://www.youtube.com/watch?v=Lzm35FxKcOY
Show What You Know
Using the information provided above, answer the following questions.
 When the water bottles were brought closer to Bill's body in the video, why did he speed up?
 Are the angular velocity and the angular momentum parallel or perpendicular to one another?