An automobile initially traveling due east on a straight, level road at 28ms−1 enters a construction zone in which the driver must reduce the car’s speed to 12ms−1 over a time interval of 4.0s. Assume the road is perfectly horizontal and straight.
(a) Calculate the magnitude and direction of the car’s average acceleration while it is passing through the construction zone.
(b) If the car were to maintain the same average acceleration found in part (a) after exiting the zone, determine the additional time required for the car to come to rest.
(c) Discuss how the sign of the average acceleration you obtained in part (a) is consistent with the physical description of the car’s motion in the eastward direction.