Velocity

Velocity is a measurement of speed in a certain direction of motion. It is a fundamental concept in kinematics, the branch of classical mechanics that describes the motion of physical objects. Velocity is a vector quantity, meaning that both magnitude and direction are needed to define it (velocity vector). The scalar absolute value (magnitude) of velocity is called , a quantity that is measured in metres per second (m/s or m⋅s−1) in the SI (International System of Units) system. For example, "5 metres per second" is a scalar, whereas "5 metres per second east" is a vector. If there is a chang

speed of electromagnetic waves in vacuum

In kinematics, the speed (commonly referred to as v) of an object is the magnitude of the change of its position over time or the magnitude of the change of its position per unit of time, it is thus a non-negative scalar quantity. The average speed of an object in an interval of time is the distance travelled by the object divided by the duration of the interval; the instantaneous speed is the limit of the average speed as the duration of the time interval approaches zero. Speed is the magnitude of velocity (a vector), which indicates additionally the direction of motion.

distance travelled during a unit of time by a sound wave propagating through an elastic medium

physical quantity defined as the rate of change of angular position whose direction is (if regarded as a vector) the axis of rotation

component of the velocity in radial direction

highest velocity attainable by an object as it falls through a fluid

thumb|330x330px|Because the sphere travels faster than light, the observer sees nothing until it has already passed. Then, two images appear: one of the sphere arriving (on the right) and one of it departing (on the left). Faster-than-light (superluminal or supercausal) travel and communication are the conjectural propagation of matter or information faster than the speed of light in vacuum (). The special theory of relativity implies that only particles with zero rest mass (i.e., photons) may travel at the speed of light, and that nothing may travel faster.

equation used in relativistic physics

velocity of an object or observer B in the rest frame of another object or observer A

thumb|upright=0.85|Rapidity is the value of for velocity and speed of light

horizontal speed of an aircraft relative to the ground

speed at which relativistic effects become significant

physical constant equal to the speed of light

cycling term; number of revolutions of the crank per minute

two separate velocities in machine tool practice, cutting speed and feed rate

vector field which is used to mathematically describe the motion of a continuum

ratio of the speed at which a wavefront passes through the medium to the speed of light in a vacuum

Concept in physics

thumb|The "energy flash" of a hypervelocity impact during a laboratory simulation of what happens when a piece of orbital debris hits a spacecraft in orbit thumb|The aftermath of a hypervelocity impact, with a projectile the same size as the one that impacted for scale

Hypothetical flow velocity

aspect of nerve conduction studies

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alternative to velocity for measuring motion in relativity theory