$$\begin{aligned} \tau & =\mathrm{I} \alpha \Rightarrow \alpha=\frac{\tau}{\mathrm{I}}=\frac{100}{300}=\frac{1}{3} ~\mathrm{rad} / \mathrm{sec}^2 \\ \omega_{\mathrm{i}} & =0 \\ \omega_{\mathrm{f}} & =\omega_{\mathrm{i}}+\alpha \mathrm{t} \\ & =0+\frac{1}{3} \times 3 \\ \omega_{\mathrm{f}} & =1 ~\mathrm{rad} / \mathrm{sec}\end{aligned}$$