Ana follows a twisting 90 m path through a garden and ends 40 m north of the bench where she started. What is her displacement?
You've already seen the other kind of quantity waiting for its name: a displacement of 10 m is not yet a complete description. 10 m, which way?
A displacement of 10 m is incomplete until you say 10 m east. Some quantities need both a size and a direction before they say anything definite.
A quantity that needs both a size and a direction to be complete is called a vector.
What is a vector?
Physicists call a vector's size its magnitude. The magnitude of the displacement 10 m east is 10 m.
A forecast states the wind's velocity as '15 mph'. Why is the statement incomplete?
Take the displacement 5 m north, drawn as an arrow. The length shows the magnitude: 5 m. The arrowhead points in the vector's direction: north.
A gardener who states a displacement as '3 m' has given the magnitude and left the direction off. Say 3 m toward the shed, and the vector is complete.
Two displacement arrows are drawn to the same scale. Arrow A is twice as long as arrow B, and both point the same way. What does the drawing say?
A pilot must report the plane's velocity to a controller. Which report is complete?
A vector is drawn as an arrow on a scaled diagram. Which change to the arrow would change the vector's DIRECTION without changing its magnitude?
A student claims that 'east' by itself is a vector, because it has a direction. What is wrong with the claim?