Starting from rest, a truck travels in a straight line for 9.0 s with a uniform acceleration of +1.5 m/s?. The driver then applies the brakes for 2.0 s, causing a uniform acceleration of -2.0 m/s2 over that time. (a) What is the truck's speed (in m/s) at the end of the braking period? (b) What is the total distance traveled by the truck in meters (from the point where it started at rest to the end of the braking period)