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simply. speed. Rate at which an object’s position changes in a specific direction over time. A vector quantity. See acceleration and vector.

velocity (Wikipedia)

Velocity is the speed in combination with the direction of motion of an object. Velocity is a fundamental concept in kinematics, the branch of classical mechanics that describes the motion of bodies.

Velocity
As a change of direction occurs while the racing cars turn on the curved track, their velocity is not constant even if their speed is.
Common symbols
v, v, v, v
Other units
mph, ft/s
In SI base unitsm/s
DimensionL T−1

Velocity is a physical vector quantity: both magnitude and direction are needed to define it. The scalar absolute value (magnitude) of velocity is called speed, being a coherent derived unit whose quantity is measured in the SI (metric system) as metres per second (m/s or m⋅s−1). For example, "5 metres per second" is a scalar, whereas "5 metres per second east" is a vector. If there is a change in speed, direction or both, then the object is said to be undergoing an acceleration.

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