A speed boat is moving across the surface of a lake. At time t1 = 0 with the components of its velocity are vx = 25 m/s and vy = -10 m/s. At time t2 = 15 s the components are vx = 12 m/s and vy = -21 m/s. (a) what was the change in the magnitude and direction of the boat’s velocity through this time? (b) What are the components of the average acceleration for this interval? (c) What are the magnitude and direction of the average acceleration for this interval?