Question

Sarah wanted to know the velocity of an airplane traveling from Houston to Dallas. After recording the distance (in miles) and time (in hours) it took to travel to Dallas, what other measurement does Sarah need to determine the airplanes velocity?

Answer 1

She would need to know the direction that the plane took. Velocity is a vector so it needs a speed which she has by having the distance and time it took to travel, but a vector also has direction in addition to it.

Answer 2

Sarah needs to know also the direction of the airplane.

In fact, the velocity of an object is a vector, which means it has

a) a Magnitude (the speed)

b) a direction

Knowing the distance and the time, Sarah is only able to calculate the speed (which is the magnitude of the velocity), given by

$v=\frac{distance}{time}$

but in order to give complete information about the velocity, she also needs to know the direction of the airplane.