2-1 할리데이 11판 솔루션 일반물리학

풀이자주 : 문제의 유효숫자가 애매하여 다양하게 표현했습니다. $$ \begin{cases} g &=9.80665\ut{m/s^2}\\ H &=4000\ut{m}\\ v_0 &= 0 \end{cases} $$ $$\ab{a}$$ $$ \begin{aligned} 2aS&=v^2-{v_0}^2,\\ 2(-g)(-H)&=v^2\\ \end{aligned} $$ $$ \begin{aligned} v&=\sqrt{2gH}\\ &=\sqrt{2(9.80665\ut{m/s^2})(4000\ut{m})}\\ &=\sqrt{\frac{392266}{5}}\ut{m/s}\\ &\approx 280.0949838893942\ut{m/s}\\ &\approx 2.801\times10^2\ut{m/s}\\ &\approx 2.8\times10^2\ut{m/s}\\ &\approx 3\times10^2\ut{m/s}\\ \end{aligned} $$ $$\ab{b}$$ $$\title{Not Safe} $$