2-32 할리데이 10판 솔루션 일반물리학

$$\begin{aligned} v_0 &= 1020\ut{km/h} \\ &= 1020\ut{km/h}\cdot\frac{1000\ut{m}}{1\ut{km}}\cdot\frac{1\ut{h}}{3600\ut{s}} \\ &= \frac{850}{3}\ut{m/s} \end{aligned}$$ $$\begin{cases} v_0 &= \frac{850}{3}\ut{m/s} \\ t &= 1.4\ut{s} \\ v &= 0 \\ g &=9.80665\ut{m/s^2} \end{cases}$$ $$\frac{a}{g} = ?$$ $$v=v_0+at,$$ $$\begin{aligned} \frac{a}{g}&= \frac{v-v_0}{gt} \\ &= \frac{-(\frac{850}{3}\ut{m/s})}{(9.80665\ut{m/s^2})(1.4\ut{s})} \\ &= -\frac{85000000}{4118793} \\ &\approx -20.63711383407712 \\&\approx -21 \end{aligned}$$ $$\therefore a\approx-21g$$