Question

A truck travelling due north at 20m/s turns west and travels at same speed. The change in velocity be

Answer 1

Initial Velocity = 20 j (assuming +ve y axis to be along north)
Finall Velocity = - 20 i (assuming +ve x axis to be along east)
Change in Velocity = Final Velocity - Initial Velocity
= - 20 i - 20 j
Which is 20 sqrt (2) along south west.
Note that change in velocity is final velocity - initial velocity and not vice versa and hence change in velocity is along south west and not along north east or any other direction.