# A figure skater spinning at 3.4 rad/sec with a moment of inertia of 3.2 kgm2 puts his arms out so that his new moment of inertia is 4.5 kgm2. What is his new angular speed?

Jun 8, 2015

Consider conservation of angular momentum you get:
Ang. Mom. (before)=Ang. Mom (after)
Where Ang. Mom. $= L = I \cdot \omega$
Where:
$I =$ moment of inertia
$\omega =$ angular speed
So:
$3.2 \cdot 3.4 = 4.5 \cdot {\omega}_{a f t}$
${\omega}_{a f t} = 2.4 \frac{r a d}{\sec}$
The skater slows down his rotaton by opening his arms.