A material transport elevator moving upward with a constant velocity of 6 ft/sec overtakes an administrative personnel elevator that is stopped. Four seconds later, the personnel elevator begins its upward motion with a constant acceleration of 2.4 ft/sec.^2. Determine a) when and where the elevators will be at the same height, b) the speed of the personnel elevator at that time.

  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.

i really dont know but i will try okay.

so i think u would just add all them up and get your answer..

3. dark matter

empty space could also be a simple vacuum