Why does a traveller's bag have wheels

It's convenient and easy to rove a traveller's bag when it has wheels. You could easily drag the bag without hesitation instead of lifting it or pushing it heavily.

answer; equivalent to a one(1) horsepower motor;

  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.