The distance from the surface where the is measured as the hydrodynamic boundary layer thickness. The local exterior velocity is the same as the speed.
<h3>What is velocity?</h3>
Velocity is the direction at which an object is moving and serves as a measure of the rate at which its position is changing as seen from a specific point of view and as measured by a specific unit of time (for example, 60 km/h northbound).
In kinematics, the area of classical mechanics that deals with the motion of bodies, velocity is a fundamental idea.
A physical vector quantity called velocity must have both a magnitude and a direction in order to be defined.
Speed is the scalar absolute value (magnitude) of velocity; it is a coherent derived unit whose quantity is measured in metres per second (m/s or ms1) in the SI (metric system).
<h3>What is speed?</h3>
The speed of an object, also known as v in kinematics, is the size of the change in that object's position over time or the size of the change in that object's position per unit of time, making it a scalar quantity.
The instantaneous speed is the upper limit of the average speed as the duration of the time interval gets closer to zero.
The average speed of an object in a period of time is the distance traveled by the object divided by the duration of the interval.
