Velocity

Velocity, in everyday language often called speed, is a physical quantity that describes how quickly an object changes its position. It is defined as the distance an object travels divided by the time it takes to cover that distance, so a larger distance in a shorter time means a higher velocity. In physics a careful distinction is drawn: speed tells you only how fast something moves, while velocity also includes the direction of motion. Velocity can be constant, as with a car cruising steadily on a highway, or it can change from moment to moment, giving us what is called instantaneous velocity. It is commonly measured in metres per second or kilometres per hour, and these units can be converted from one to the other.

Understanding velocity matters far beyond the classroom: it lets drivers judge journey times, helps engineers design safe vehicles and roads, and underpins fields from athletics and aviation to astronomy, where it describes everything from a sprinter's pace to the motion of planets.