What is the distance after moving 3 m east and 3 m west?	6 m.
What is the displacement after returning to the starting position?	Zero.
What is the average speed for 12 m in 4 s?	3 m/s.
Can changing direction at constant speed involve acceleration?	Yes, because velocity includes direction.
For constant mass in an inertial frame, what acceleration follows from a 6 N resultant force on 2 kg?	3 m/s² in the resultant force direction.
Does zero resultant force require zero velocity in that model?	No. It requires zero acceleration.