8-63 할리데이 11판 솔루션 일반물리학

$$ \begin{cases} \Delta y &= -14\ut{m}\\ v_i&=-3.0\ut{m/s}\\ v_f&=-14\ut{m/s}\\ g&=9.80665\ut{m/s^2}\\ \end{cases} $$ $$ \put \begin{cases} \KE : \text{Kinetic Energy}\\ \GE : \text{Gravitational Potential Energy}\\ \end{cases} $$ $$ \begin{aligned} \Ans&=-\frac{\Delta \KE}{\Delta \GE}\\ &=-\frac{\Delta \(\frac{1}{2}m{v}^2\)}{\Delta (mgy)}\\ &=\frac{\Delta \({v}^2\)}{2g(-\Delta y)}\\ &=\frac{{v_f}^2-{v_i}^2}{2g(-\Delta y)}\\ &=\frac{187}{28g}\\ &\approx 0.681024756524545\\ &\approx 68.1024756524545\%\\ &\approx 68\%\\ \end{aligned} $$