5-50 할리데이 11판 솔루션 일반물리학

$$\begin{cases} m_A&=13\ut{kg}\\ m_B&=20\ut{kg} \end{cases}$$ $$\ab{a}$$ $$\Sigma \vec F = m\vec a,$$ $$\begin{cases} \Sigma F_A &= m_A a_A\\ \Sigma F_B &\ge0\\ \end{cases}$$ $$\begin{cases} T-m_Ag &= m_A a_A\\ T &\gt m_Bg\\ \end{cases}$$ $$\begin{aligned} a&\ge\frac{7}{13}g\\ &~~~~\approx5.280503846153846\ut{m/s^2}\\ &~~~~\approx5.3\ut{m/s^2}\\ \end{aligned}$$ $$\ab{b}$$ $$\Sigma \vec F = m\vec a,$$ $$\begin{cases} \Sigma F_A &= m_A a\\ \Sigma F_B &= m_B a\\ \end{cases}$$ $$\begin{cases} T-m_Ag &= m_A a\\ m_Bg-T &= m_B a\\ \end{cases}$$ $$\ab{b}$$ $$\begin{aligned} a&=\frac{7}{33}g\\ &\approx 2.0801984848484847\ut{m/s^2}\\ &\approx 2.1\ut{m/s^2}\\ \end{aligned}$$ $$\ab{c}$$ $$y+$$ $$\ab{d}$$ $$\begin{aligned} T&=\frac{520}{33}g\\ &\approx 154.5290303030303\ut{N}\\ &\approx 1.5\times10^2\ut{N}\\ \end{aligned}$$