Đáp án:
\(\begin{array}{l}
{v_1} = 187,5m/s\\
\alpha = 53,13^\circ
\end{array}\)
Giải thích các bước giải:
\(\begin{array}{l}
{p_1} = \sqrt {{p^2} + p_2^2} \\
{m_1}{v_1} = \sqrt {{{(({m_1} + {m_2})v)}^2} + {{({m_2}{v_2})}^2}} \\
{v_1} = \frac{{\sqrt {{{(({m_1} + {m_2})v)}^2} + {{({m_2}{v_2})}^2}} }}{{{m_1}}} = \frac{{\sqrt {{{((4 + 8)100)}^2} + {{(4.225)}^2}} }}{8} = 187,5m/s\\
\tan \alpha = \frac{{{p_2}}}{p} = \frac{{(({m_1} + {m_2})v)}}{{{m_2}{v_2}}} = \frac{{(4 + 8)100}}{{4.225}} = \frac{4}{3}\\
\alpha = 53,13^\circ
\end{array}\)