12-38 할리데이 11판 솔루션 일반물리학

$$ \begin{cases} H&=59.1\ut{m}\\ 2R&=7.44\ut{m}\\ \Delta x_{\text{top}0} &= 4.01\ut{m}\\ \end{cases} $$ $$\ab{a}$$ $$\Delta x_\com = R,$$ $$ \begin{aligned} \Delta x_{\text{top}}&=2\Delta x_\com\\ &=2R\\ \end{aligned} $$ $$ \begin{aligned} \Ans&=2R-\Delta x_{\text{top}0}\\ &=3.43\ut{m} \end{aligned} $$ $$\ab{b}$$ $$ \begin{aligned} \theta&=\sin^{-1}{2R\over H}\\ &=\sin^{-1}{124\over 985}\\ &\approx 0.12622322910580994\ut{rad}\\ &\approx 0.126\ut{rad}\\ \end{aligned} $$