Đáp án:
\(\begin{array}{l}
a.\\
{v_2} = \frac{{20}}{9}m/s\\
b.\\
{v_2} = \frac{{50}}{9}m/s
\end{array}\)
Giải thích các bước giải:
\(\begin{array}{l}
a.\\
p = p'\\
{m_1}{v_1} - {m_2}{v_2} = 0\\
{v_2} = \frac{{{m_1}{v_1}}}{{{m_2}}} = \frac{{0,5.4}}{{0,9}} = \frac{{20}}{9}m/s\\
b.\\
p = p'\\
{m_1}{v_1} - {m_2}{v_2} = - {m_1}{v_1}'\\
{v_2} = \frac{{{m_1}{v_1} + {m_1}{v_1}'}}{{{m_2}}} = \frac{{0,5.4 + 0,5.6}}{{0,9}} = \frac{{50}}{9}m/s
\end{array}\)