10-3 할리데이 11판 솔루션 일반물리학

$$ \begin{cases} \theta_i&=102\degree\\ w&=-\frac{360}{24}\ut{\degree/h}=-15\ut{\degree/h}\\ \end{cases} $$ $$\ab{a}$$ $$\theta_f=25\degree$$ $$\Delta \theta=\omega t$$ $$ \begin{aligned} t&=\frac{\Delta \theta}{\omega}\\ &=\frac{25\degree-102\degree}{-15\ut{\degree/h}}\\ &=\frac{77}{15}\ut{h}\\ &\approx 5.133333333333334\ut{h}\\ &\approx 5.1\ut{h} \end{aligned} $$ $$\ab{b}$$ $$\theta_f=-20\degree$$ $$ \begin{aligned} t&=\frac{\Delta \theta}{\omega}\\ &=\frac{-20\degree-102\degree}{-15\ut{\degree/h}}\\ &=\frac{122}{15}\ut{h}\\ &\approx 8.133333333333333\ut{h}\\ &\approx 8.1\ut{h} \end{aligned} $$