2-36 할리데이 11판 솔루션 일반물리학

$$ \begin{cases} v_{A1}&=v_{A2}=40\ut{km/h}\\ v_{B}&=52\ut{km/h}\\ \Delta x_{A}&=60\ut{km} \end{cases} $$ $$ \begin{aligned} \Delta x_A&=v_{A1}t+v_{A2}t\\ t&=\frac{\Delta x_A}{v_{A1}+v_{A2}}\\ &=\frac{\Delta x_A}{2v_{A1}}\\ \Sigma \Delta x_B&=v_Bt\\ &=v_B\cdot \frac{\Delta x_A}{2v_{A1}}\\ &= \frac{\Delta x_A}{2}\cdot\frac{v_B}{v_{A1}}\\ &= \frac{60\ut{km}}{2}\cdot\frac{52\ut{km/h}}{40\ut{km/h}}\\ &=39\ut{km} \end{aligned} $$