4-22 할리데이 10판 솔루션 일반물리학

$$\begin{cases} h &= 1.50\ut{m}\\ \Delta x &= 1.52\ut{m}\\ \vec a &= -g\j\\ g &\approx 9.80665\ut{m/s^2}\\ \end{cases}$$
(a) $t=?$ $$\begin{aligned} \Delta y &= v_{y0}t+\frac{1}{2}a_yt^2,\\ -1.5 &= (0)t+\frac{1}{2}(-g)t^2\\ 1.5 &= \frac{1}{2}gt^2\\ \end{aligned}$$ $$\begin{aligned} t&=\sqrt{\frac{3}{g}}\\ &\approx 0.553095709524\ut{sec}\\ &\approx 0.553\ut{sec}\\ \end{aligned}$$
(b) $v_0=?$ $$\begin{aligned} \Ans &= v_0 =v_x\\ v_x &= \frac{\Delta x}{t}\\ &=\frac{1.52}{\sqrt{\frac{3}{g}}}\\ &\approx2.74816812683\ut{m/s}\\ &\approx2.75\ut{m/s}\\ \end{aligned}$$