2-25 할리데이 10판 솔루션 일반물리학

$$\begin{cases} t&=2.5\ut{s} \\S &= 8.0\ut{m}-2.0\ut{m} = 6.0\ut{m} \\ v_0 &= 2.8\ut{m/s} \\ a &= \Cons \end{cases}$$ $$a=?$$ $$S = v_0t+\frac{1}{2}at^2$$ $$\begin{aligned} \\ \Ans &= a = \frac{2(S-v_0t)}{t^2} \\ &= \frac{2\{6.0\ut{m}-(2.8\ut{m/s})(2.5\ut{s})\}}{(2.5\ut{s})^2} \\ &= -\frac{8}{25}\ut{m/s^2} \\ &= -0.32\ut{m/s^2} \end{aligned}$$