In some cases an engineer might be interested in the interaction between two particles, and how their momentum would relate to each other. The conservation of linear momentum states that one particles momentum would equal the other particles momentum assuming there is no loss of energy. This is represented in equation 1.

**(Eq 1)**$m_1v_1 = m_2v_2$

m_{1} = mass of particle 1

m_{2} = mass of particle 2

v_{1} = velocity of particle 1

v_{2} = velocity of particle 2