Editing Velocity (section)

= Velocity: Definition and Mathematical Representation =

== Introduction ==
'''Velocity''' is a fundamental concept in physics that describes the rate at which an object changes its position with respect to time. Unlike speed, velocity is a '''vector quantity'''—it has both magnitude and direction.

Velocity is essential in kinematics, dynamics, and many real-world applications such as vehicle motion, projectile paths, and orbital mechanics.

== Definition ==

The instantaneous velocity is defined as the time derivative of displacement:

<math>
\vec{v} = \frac{d\vec{s}}{dt}
</math>

Where:
* <math>\vec{v}</math> is the velocity vector,
* <math>\vec{s}</math> is the displacement vector,
* <math>t</math> is time.

== Average Velocity ==

Average velocity over a time interval is given by:

<math>
\vec{v}_{\text{avg}} = \frac{\Delta \vec{s}}{\Delta t}
</math>

Where:
* <math>\Delta \vec{s}</math> is the change in displacement,
* <math>\Delta t</math> is the change in time.

== SI Unit ==

The SI unit of velocity is:

<math>
\mathrm{m/s} \quad \text{(meters per second)}
</math>

== Velocity vs. Speed ==
* '''Velocity''' includes direction; it’s a vector.
* '''Speed''' is the magnitude of velocity; it’s a scalar.

Example: An object moving in a circle at constant speed has changing velocity due to direction change.

== Motion with Constant Acceleration ==
When acceleration is constant, the following kinematic equation relates velocity and time:

<math>
v = u + at
</math>

Where:
* <math>v</math> is the final velocity,
* <math>u</math> is the initial velocity,
* <math>a</math> is the acceleration,
* <math>t</math> is time.

== Relative Velocity ==
The velocity of object A with respect to object B is:

<math>
\vec{v}_{A/B} = \vec{v}_A - \vec{v}_B
</math>

This concept is crucial in problems involving two or more moving observers or reference frames.

== Graphical Interpretation ==
* The slope of a displacement–time graph gives velocity.
* The area under a velocity–time graph gives displacement.

== Applications ==
* Vehicle dynamics and navigation
* Ballistic and projectile motion
* Fluid flow (e.g., velocity fields in aerodynamics)
* Orbital mechanics and astronomy

== See Also ==
* [[Acceleration]]
* [[Displacement]]
* [[Speed]]
* [[Kinematics]]
* [[Relative Motion]]
* [[Graphical Analysis of Motion]]