Question

which is a vector quantity, speed or velocity? defend your answer.

Answer 1

Velocity is a vector quantity. A vector must have magnitude and direction. Speed only tells you how fast you are going, and hence is just a magnitude. I could say for example that I was travelling at 60 mph. Velocity on the other hand is a vector and has speed and direction. I would say I was travelling 60 mph south.

If you think about being an aircraft controller, it would mean nothing if you just knew the speeds of all the planes in air. You would want to know the speeds and the direction they are travelling in order to prevent mid-air collisions. therefore you would want to know their velocity. It is no accident that when pilots talk to other pilot or air-traffic controllers they talk about what their vectors are.