Đáp án:
\(\begin{array}{l}
a.\\
{v_2}' = 1,8m/s\\
b.\\
Q = - 8,4
\end{array}\)
Giải thích các bước giải:
\(\begin{array}{l}
a.\\
p = p'\\
{m_1}{v_1} - {m_2}{v_2} = - {m_1}{v_1}' + {m_2}{v_2}'\\
3.1 - 2.3 = - 3.2,2 + 2.{v_2}'\\
{v_2}' = 1,8m/s\\
b.\\
p = p'\\
{m_1}{v_1} - {m_2}{v_2} = ({m_1} + {m_2})v'\\
3.1 - 2.3 = (3 + 2)v'\\
v' = - 0,6m/s\\
Q = {W_d} - {W_d}' = \frac{1}{2}{m_1}v_1^2 - \frac{1}{2}{m_2}v_2^2 - \frac{1}{2}({m_1} + {m_2})v{'^2} = \frac{1}{2}{3.1^2} - \frac{1}{2}{2.3^2} - \frac{1}{2}(2 + 3){( - 0,6)^2} = - 8,4
\end{array}\)