9-43 할리데이 11판 솔루션 일반물리학

$$\begin{cases} x_P&=0\\ x_Q&=1.0\ut{m}\\ m_P&=0.10\ut{kg}\\ m_Q&=0.30\ut{kg}\\ F&=1.0\times10^{-2}\ut{N}\\ \end{cases}$$ $$\ab{a}$$ $$\Delta \Sigma \vec p=0,$$ $$\vec p_{\com i}=\vec p_{\com f},$$ $$\vec v_{\com i}=\vec v_{\com f}=0$$ $$\ab{b}$$ $$\begin{aligned} x_{\text{crash}}&=x_\com\\ &=\frac{\Sigma xm}{M}\\ &=\frac{x_Pm_P+x_Qm_Q}{m_P+m_Q}\\ &=\frac{3}{4}\ut{m}\\ &=0.75\ut{m} \end{aligned}$$