12-31 할리데이 11판 솔루션 일반물리학

$$\begin{cases} m_1&=85.0\ut{kg}\\ m_2&=30.0\ut{kg}\\ L_2&=2.00\ut{m}\\ m_3&=20.0\ut{kg}\\ d&=0.500\ut{m}\\ L_1&=L_2+2d\\ \end{cases}$$ $$\begin{cases} \Sigma F_{1y}&=0\\ \Sigma \tau_1&=0\\ \Sigma F_{2y}&=0\\ \Sigma \tau_2&=0\\ \end{cases}$$ $$\begin{cases} 0&=T_{1L}+T_{1R}-T_{2L}-T_{2R}-m_1g\\ 0&=-dT_{2L}-{L_1\over2}m_1g-\br{L_1-d}T_{2R}+L_1T_{1R} \\ 0&=T_{2L}+T_{2R}-m_2g-m_3g\\ 0&=-dm_3g-{L_2\over2}m_2g+L_2T_{2R} \\ \end{cases}$$ $$\begin{aligned} T_{1R}&=\frac{1}{2} \br{m_1 g+m_2g+\frac{4 d }{L_1}m_3 g}\\ &={385\over6}g\\ &={15102241\over24000}\ut{N}\\ &\approx 629.2600416666667\ut{N}\\ &\approx 629\ut{N}\\ \end{aligned}$$