Answer
$28.18\ rad/s^2$
Work Step by Step
Given:
The initial angular velocity $\omega_o = 0$
The final angular velocity $\omega = 6.20\ rad/s$
Time $t =220\ ms$
Rotational inertia about her center of mass is $I = 12\ kg.m^2$
From the rotational kinematics equation, we have:
$\omega = \omega_o + \alpha t$
where $\alpha$ is the angular acceleration
We rearrange the equation and solve for $\alpha$:
$\alpha = \frac{\omega-\omega_o}{t}$
$\alpha = \frac{6.2\ rad/s^2-0}{0.220\ s}$
$\alpha= 28.18\ rad/s^2$
