Answer
a) $\theta=4600rad$
b) $\alpha=200rad/s^2$
Work Step by Step
The initial speed is $\omega_0=420rad/s$, the final speed is $\omega=1420rad/s$, and the time is $t=5s$
a) The angle through which the rotor turns is $$\theta=\Big(\frac{\omega+\omega_0}{2}\Big)t=4600rad$$
b) The magnitude of the angular acceleration is $$\alpha=\frac{\omega-\omega_0}{t}=200rad/s^2$$
