## Physics (10th Edition)

a) $\overline\alpha=+0.75rad/s^2$ b) $\overline\alpha=-0.75rad/s^2$ c) $\overline\alpha=+1rad/s^2$ d) $\overline\alpha=-2rad/s^2$
We have $$\overline\alpha=\frac{\Delta \omega}{\Delta t}=\frac{\omega-\omega_0}{\Delta t}$$ a) $$\overline\alpha=\frac{(+5)-(+2)}{4}=+0.75rad/s^2$$ b) $$\overline\alpha=\frac{(+2)-(+5)}{4}=-0.75rad/s^2$$ c) $$\overline\alpha=\frac{(-3)-(-7)}{4}=+1rad/s^2$$ d) $$\overline\alpha=\frac{(-4)-(+4)}{4}=-2rad/s^2$$