Question

Two sports cars speeding along SLEX pass each other. Car A is headed North with a speed of 40m/s, while Car B is headed South with a speed of 38 m/s, both velocities relative to the Earth. From the perspective of Car B, what is the velocity of Car A?

Answer 1

From the perspective of car B, the velocity of car A is

$$v_{A-B}=v_A+v_B=78\text{ m/s}.$$