In a drag race, the position of a car as a function of time is given by x = bt² with b = 2.000 m/s² In an attempt to determine the car's velocity midway down a 400 -m track, two observers stand at the 180 -m and 220 -m marks and note when the car passes.
What value do the two observers compute for the car's velocity over this 40 -m stretch?