2-14 할리데이 10판 솔루션 일반물리학

$$x = 16te^{-t}$$ $$\Ans = \abs{x(t_{\dot x=0})} =?$$ $$\begin{aligned} \dot x &= \dxt{x} \\&= \dt(16te^{-t}) \\&= 16 e^{-t}-16 te^{-t} \\&= -16 e^{-t} (t-1) = 0 \end{aligned}$$ $$t=1\ut{s}$$ $$\begin{aligned} \\\abs{x(1)} &= \abs{16(1)e^{-(1)}} \\ &= \frac{16}{e}\ut{m} \\&\approx 5.886071058743077\ut{m} \end{aligned}$$