2-22 할리데이 11판 솔루션 일반물리학

$$\ab{a}$$ $$ \begin{aligned} v&=v_0+at,\\ 3.0\times10^8\cdot\frac{0.1}{100}&=0+(9.8)t\\ \end{aligned} $$ $$ \begin{aligned} t&=\frac{1500000}{49}\ut{s}\\ &=\frac{25000}{49}\ut{min}\\ &=\frac{1250}{147}\ut{h}\\ &=8\ut{h}+30\ut{min}+\frac{600}{49}\ut{s}\\ &\approx8\ut{h}+30\ut{min}+12.24489795918367\ut{s}\\ &\approx8\ut{h}+30\ut{min}+12\ut{s}\\ \end{aligned} $$ $$\ab{b}$$ $$ \begin{aligned} S&=v_0t+\frac{1}{2}at^2,\\ &=(0)t+\frac{1}{2}(9.8)\(\frac{1500000}{49}\)^2\\ &=\frac{225000000000}{49}\ut{m}\\ &\approx 4.591836734693877\times 10^9\ut{m}\\ &\approx 4.6\times 10^9\ut{m}\\ &\approx 15\ut{light~second} \end{aligned} $$