You might have experienced static electricity and even felt a mild shock?

Yes, uh huh, you better believe it, I sure have. Sometimes they were not so mild.

prolly a beacuse the momentuem the car has increases while going down hill

  distance on the y-axis and time on the x-axis.

explanation:

the instantaneous velocity = change in position/time taken

the slope of the graph should give instantaneous velocity.

  slope of a graph = change in value of y -axis / change in values of x -axis

  comparing both the equations

    change in value of y -axis = change in position

  change in values of x -axis = time taken

so position values should be on the y axis and time values should be on the x axis.

distance on the y-axis and time on the x-axis.