10-34 할리데이 11판 솔루션 일반물리학

$$ \begin{cases} \omega_i&=160\ut{rad/s}\\ \alpha&=-4.0\ut{rad/s^2}\\ \omega_f&=0\\ \end{cases} $$ $$\omega=\omega_0+\alpha t,$$ $$\ab{a}$$ $$ \begin{aligned} t&=\frac{\omega_f-\omega_i}{\alpha}\\ &=40\ut{s}\\ &=4.0\times10\ut{s}\\ \end{aligned} $$ $$\ab{b}$$ $$2\alpha \Delta \theta=\omega^2-{\omega_0}^2,$$ $$ \begin{aligned} \Delta \theta&=\frac{{\omega_f}^2-{\omega_i}^2}{2\alpha}\\ &=3200\ut{rad}\\ &=3.2\times10^3\ut{rad}\\ \end{aligned} $$