Question

A glowing blue mote of mass 32.3 g is traveling east at 4.50 m/s when it collides and merges with another mote of mass 78.0 g that is traveling west at 1.12 m/s. Find the velocity of the motes after they merge together (be sure to include direction).

Answer 1

Use the law of conservation of momentum
\[m_{1}v_{1}+m_{2}v_{2}=(m_{1}+m_{2})v\]
as velocity is a vector quantity, in one dimensional motion you don't really need to use vectors because you can simply indicate one direction as positive and the opposite as negative, so be careful about the sign of your velocities