You will not receive full credit for physics calculations if this is not done. To measure movement, some point must be considered as nonmoving. After lunch you travel 150 miles in an hour and a half. Speed only gives distance and time. Velocity gives distance, time, and the direction of travel.
Velocity is known as a vector quantity because it has both speed and direction .
Vectors can be use to graphically represent the mathematics of motion. The vector diagram here might represent the motion of an airplane. The first blue arrow shows the speed and heading of the plane. The second blue arrow shows the speed and direction the wind is blowing. Since the wind is changing the speed and direction of the plane, the two vectors are added, head to tail, to determine the actual speed and direction traveled.