The radius of the track is 150 m. So, going halfway around the track would make the displacement just be the diameter. The diameter is 2 multiplied by the radius, so the displacement is 300 m. When the car travels the full lap, it goes back to its starting position, so the displacement is 0.
Work Step by Step
displacement = (Final Position) - (Initial Position) Since the car traveled halfway, the displacement is the diameter. Diameter = 2 x radius Diameter = 2 x 150 m Diameter = Displacement = 300m.