What is a Vector?
Physicists use two different kinds of quantities, scalar quantities
and vector quantities. Scalar quantities, like mass,
volume, and speed, have one component -- whatever it is that you're measuring.
Vector quantities include a scalar component, called magnitude,
and also a directional component. Velocity, for example, is speed in
a certain direction. Other common vectors are force and acceleration.
In the image to the left, the red arrow indicates the force pushing the rocket up. Forces always include a directional component, which in this case points straight up. The length of the arrow indicates how strong the force is: the longer the arrow, the greater the force.