posted by kevin .
what is the displacement of the ball?
i.imgur. com/8ljWh . png
i don't know calculus!
You do not really need calculus. Just use the AVERAGE velocity between the start and end times.
between 0 and 2, the average is 1.5 for 2 seconds so displacement is 3
between 0 and 4, the average is 0 so displacement is zero
between 4 and 4 the average is -1.5 so displacement is -3