4-22 할리데이 11판 솔루션 일반물리학

$$ \begin{cases} t_0:\text{Start}\\ t_1:\text{Hight Max}\\ v_0 = 4v_1\\ \end{cases} $$ $$ \begin{cases} \vec v_0 &= v_0\cos\theta\i+v_0\sin\theta\j\\ \vec v_1 &= v_1\i\\ \end{cases} $$ $$ \begin{aligned} v_1&=v_0\cos\theta\\ \cos\theta_0&=\frac{v_1}{v_0}\\ &=\frac{v_1}{4v_1}\\ &=\frac{1}{4}\\ \end{aligned} $$ $$ \begin{aligned} \theta_0&=\cos^{-1}\frac{1}{4}\\ &\approx 1.318116071652818\ut{rad}\\ \end{aligned} $$