A mass $m_1$ moving at speed $u_1$ collides with a mass $m_2$ moving at speed $u_2$ in the same direction. Following the collision, mass $m_1$ has speed $v_1$ and mass $m_2$ has speed $v_2$ in the same direction. The collision is perfectly elastic. Which equation is not correct?
- A$m_1 u_1^2 - m_1 v_1^2 = m_2 v_2^2 - m_2 u_2^2$
- B$v_2 + u_2 = v_1 + u_1$
- C$m_1 (u_1 - v_1) = m_2 (v_2 - u_2)$
- D$m_1 (u_1 - v_1)^2 = m_2 (u_2 - v_2)^2$