Final answer:
Velocity is a vector quantity describing both the speed and direction of motion, pivotal to calculating other physics quantities like momentum, and is distinct from speed, a scalar quantity without direction.
Step-by-step explanation:
Velocity is a fundamental concept in physics which describes both the speed and direction of an object's motion. Unlike speed, which is a scalar quantity indicating how fast an object is moving, velocity is a vector quantity. This means it includes both a magnitude (how fast the object moves) and a direction (where it is heading). For example, a car traveling at 20 kilometers per hour due south has a velocity, whereas 20 kilometers per hour without a direction specified is merely the speed.
Importance of velocity in physics cannot be overstated, as it allows for the calculation of other physical quantities such as momentum, which is defined as an object's mass times its velocity. Furthermore, understanding velocity is crucial for analyzing motion in terms of both average velocity (displacement over a time period) and instantaneous velocity (velocity at a specific point in time).
The distinction between velocity and speed is also crucial when constructing vector diagrams, which are essential tools in physics for understanding relative motion and solving problems involving forces and motion.