1. 4.0 seconds after being stopped at a stop sign, you are traveling again at 31 km/h . At what acceleration did your car speed up?

2. The maximum amplitude of acceleration a car can do is determined by the friction between the tire and the road. If the tire on a car has a static friction coefficient of 1.1. What is the maximum acceleration this car can achieve? (give your answer in the unit of)

3. A car traveling at 67 km/h comes to an abrupt halt in 0.35 second when it hits a tree. What is the magnitude of the deceleration in "meters per second per second" of the car?