Grade 11 Physics A local police department has decided to use airplanes to help catch drivers who are speeding. They have painted white marks on the side of the road that are 400 m apart.

a. If the speed limit on the road is 80 km/h, how long should it take to drive from one white line to another if the driver is obeying the speed limit? (Hint: convert the speed to m/s first)

b. How will the pilot of the plane know if the driver is speeding?