\begin{align} \v{v}_1' &= m_2v\v{n}_0/(m_1+m_2)+(m_1\v{v}_1+m_2\v{v}_2)/(m_1+m_2), \\ \v{v}_1' &= -m_1v\v{n}_0/(m_1+m_2)+(m_1\v{v}_1+m_2\v{v}_2)/(m_1+m_2). \end{align}