A figure skater begins spinning counterclock- wise at an angular speed of 4.6 7 rad/s. Dur-
ing a 4.2 s interval, she slowly pulls her arms
inward and finally spins at 7.3 7 rad/s.
What is her average angular acceleration
during this time interval?
Answer in units of rad/s.

Angular acceleration,

Explanation:

Given that,

Initial angular velocity,

The final angular velocity,

Time, t = 4.2 s

We need to find her average angular acceleration  during this time interval. Acceleration is the rate of change of velocity. So,

So, her average angular acceleration is .