5-37 할리데이 11판 솔루션 일반물리학

$$\begin{cases} m_A&=90.0\ut{kg}\\ m_B&=70.0\ut{kg}\\ h&=15.0\ut{m}\\ g&=9.80665\ut{m/s^2} \end{cases}$$ $$\Sigma \vec F = m\vec a,$$ $$\begin{cases} \Sigma F_A &= m_A a\\ \Sigma F_B &= m_B a\\ \end{cases}$$ $$\begin{cases} T-m_Ag &= m_A a\\ m_Bg-T &= m_B a\\ \end{cases}$$ $$\therefore a=-\frac{g}{8}$$ $$\begin{aligned} 2aS&=v^2-{v_0}^2,\\ 2\(-\frac{g}{8}\)(-h)&=v^2-0^2\\ \end{aligned}$$ $$\begin{aligned} v&=\sqrt{\frac{gh}{4}}\\ &\approx 6.064234288020212\ut{m/s}\\ &\approx 6.06\ut{m/s}\\ \end{aligned}$$