\begin{align}
v_1 \sin\theta_1 = & v_2 \sin \theta_2 \\
v_2 = & v_1 \cfrac{\sin \theta_1}{\sin \theta_2}
\end{align} \begin{align}
\cfrac{mv_1^2}{2}+U_1 & = \cfrac{mv_2^2}{2} + U_2 \\
v_2 & = \sqrt{v_1^2 + \cfrac{1}{2m}(U_1 – U_2) } \\
v_1 \cfrac{\sin \theta_1}{\sin \theta_2} & = \sqrt{v_1^2 + \cfrac{1}{2m}(U_1 – U_2) } \\
\cfrac{\sin \theta_1}{\sin \theta_2} & = \sqrt{1 + \cfrac{1}{2m v_1^2}(U_1 – U_2) }. \\
\end{align}L D Landau,E. M. Lifshitz Butterworth-Heinemann 1982-01-29














