[01.02]
the captain told the passengers that the plane is flying at 450 miles per hour. this information describes the plane's

1 velocity.
2 speed.
3 acceleration.
4 direction.

That information describes the plane's speed. 
If he had also told them what direction they were flying, then
they would have been able to put the two pieces of information
together, and they would know the plane's velocity.

Velocity is the speed of an object in a certain direction so you'd need to know speed and direction