The line on the position time graph show the velocites of different vehicles which line represents a vehicle moving at constant velocity

For some mysterious reason, we can't see the graph.

On a position/time graph, constant velocity is represented by a straight line.  Depending on the velocity, the line may be sloping up, sloping down, or horizontal.  The only thing the line on the graph CAN't be is vertical.

iron would move it is magnetic there is a mag field around the current in the wire