# Collisions problem (How should I approach it)

by Hindi
Tags: collisions
 P: 364 by cons of p, $$m_1v_{1i}=m_1v_{1f}-m_2v_{2f}$$ where v_2f is reckoned as negative By the energy conditions, $$m_1v_{1i}^2=\frac {1}{2}(m_1v_{1f}^2+m_2v_{2f}^2)$$ which gives two equations with two unknowns.
 Mentor P: 41,326 Collisions problem (How should I approach it) The equations should be: $$m_1v_{1i}=-m_1v_{1f}+m_2v_{2f}$$ $$\frac {1}{4}m_1v_{1i}^2=\frac {1}{2}(m_1v_{1f}^2+m_2v_{2f}^2)$$ (where the speeds are all positive)