alright so heres a pretty straight forward question asking to find the avg acceleration: A car with a velocity of 25m/s [E] changes its velocity to 25 m/s in 15s. Calculate avg acceleration. So i drew out the vector diagram, found the resultant velocity and solved for the avg acceleration. My answer was right but the direction was wrong. My answer was 2.4 m/s^2 [45 degrees south of east ] however, the books answer is 2.4 m/s^2 [45 degrees S of W] Can anyone explain to me why it is south of WEST and not East?