These controls in the cockpit of a commercial aircraft assist the pilot maintaining control over the velocity of the aircraft how fast it is traveling and in what direction it is traveling allowing it to land safely. Quantities that are defined by both magnitude and direction, such as velocity, are called vector quantities.

Physical quantities that we encounter in our day to day activities may fall into two main categories: Scalar quantities and vector quantities. Scalar quantities can be completely described by a single number (with appropriate unit) giving only its magnitude or size. Common examples of scalars are mass, time, speed, distance, energy. Vectors are quantities that require their magnitude and direction for their description. Acceleration, velocity, displacement and force are some of the common examples of vectors.

Key terms

• Vector: a quantity with magnitude and direction.
• Scalar: a quantity with magnitude only
• Equal vectors: vectors of equal magnitude and the same direction representing the same quantity.