| Mistake | Correction | | :--- | :--- | | Using Conservation of KE for inelastic collisions | KE is only conserved if $e=1$ (elastic). Always check the problem statement. | | Forgetting vector directions (signs) | Assign positive direction; velocities opposite to that are . | | Applying $m_1v_1 = m_2v_2$ (recoil only) | That is for explosions (internal forces). For collisions, use $m_1v_1 + m_2v_2 = (m_1+m_2)V$. | | Confusing impulse with momentum | Impulse $J = F \Delta t = \Delta p$ (change in momentum), not the momentum itself. |
A well-constructed is also a "error catcher." Here are the top five mistakes it helps correct: collision analysis answer key
The equation is deceptively simple: $$p_total = m_1v_1 + m_2v_2$$ | Mistake | Correction | | :--- |