8-61 할리데이 11판 솔루션 일반물리학

$$ \begin{cases} \frac{m}{t}&=5.5\times10^6\ut{kg}\\ \Delta y&=-50\ut{m}\\ g&=9.80665\ut{m/s^2}\\ \rho&=1000\ut{kg/m^3}\\ p&=10\ut{₩/kW\cdot h}\\ \end{cases} $$ $$ \put \begin{cases} \GE : \text{Gravitational Potential Energy}\\ \EE : \text{Electric Energy} \end{cases} $$ $$\ab{a}$$ $$ \begin{aligned} \frac{\Delta \GE}{t}&=\frac{\Delta (mgy)}{t}\\ &=\frac{mg\Delta y}{t}\\ &=\frac{m}{t}g\Delta y\\ &=275g\times10^6\\ &=2~696~828~750\ut{W}\\ &=2.7\times10^9\ut{W}\\ &=2.7\ut{GW}\\ \end{aligned} $$ $$\ab{b}$$ $$ \begin{aligned} \frac{\Delta \EE}{t}&=\frac{\Delta \GE}{t}\\ &=2~696~828~750\ut{W}\\ &\approx 2.7\times10^9\ut{W}\\ &\approx 2.7\ut{GW}\\ \end{aligned} $$ $$\ab{c}$$ $$ \begin{aligned} \Ans&=2~696~828~750\ut{W}\\ &=2~696~828.75\ut{kW}\cdot\frac{10\ut{₩}}{1\ut{kW\cdot h}}\\ &~~~~~\cdot\frac{365.25\ut{day}}{1\ut{year}}\cdot\frac{24\ut{h}}{1\ut{day}}\\ &=2364~0400~8225\ut{₩/year}\\ &\approx 2.4\times10^{11}\ut{₩/year}\\ &\approx \text{2천4백억원/연} \end{aligned} $$