Race car before and after taking a turn on a track. Its speed is 0.50 m/s before the turn after the turn. What is the change in the linear momentum of the car due to the turn?

SOLUTION: We treat the car as a system of particles. Then a Key Idea is that to get , we need the car’s linear momenta before and after the turn.

A second Key Idea is that, because these linear momenta are not directed along the same axis. we cannot find the change in linear momentum by merely subtracting the magnitude of from the magnitude of . Instead we must write the change in linear momentum as the vector equation.