constant velocity

(noun)

Motion that does not change in speed nor direction.

Examples of constant velocity in the following topics:

  • Constant Velocity

    • An object moving with constant velocity must have a constant speed in a constant direction.
    • Motion with constant velocity is one of the simplest forms of motion.
    • To have a constant velocity, an object must have a constant speed in a constant direction.
    • If an object is moving at constant velocity, the graph of distance vs. time ($x$ vs.
    • Examine the terms for constant velocity and how they apply to acceleration
  • Constant Velocity Produces a Straight-Line

    • If a charged particle's velocity is parallel to the magnetic field, there is no net force and the particle moves in a straight line.
    • If an object experiences no net force, then its velocity is constant: the object is either at rest (if its velocity is zero), or it moves in a straight line with constant speed (if its velocity is nonzero).
    • If the acceleration is zero, any velocity the particle has will be maintained indefinitely (or until such time as the net force is no longer zero).
    • If the magnetic field and the velocity are parallel (or antiparallel), then sinθ equals zero and there is no force.
    • In the case above the magnetic force is zero because the velocity is parallel to the magnetic field lines.
  • Simple Harmonic Motion and Uniform Circular Motion

    • Though the body's speed is constant, its velocity is not constant: velocity (a vector quantity) depends on both the body's speed and its direction of travel.
    • (Note that ω = v/r. ) Thus, v is a constant, and the velocity vector v also rotates with constant magnitude v, at the same angular rate ω.
    • The point P travels around the circle at constant angular velocity ω.
    • where θ=ωt, ω is the constant angular velocity, and X is the radius of the circular path.
    • Velocity v and acceleration a in uniform circular motion at angular rate ω; the speed is constant, but the velocity is always tangent to the orbit; the acceleration has constant magnitude, but always points toward the center of rotation
  • Instananeous Velocity: A Graphical Interpretation

    • Instantaneous velocity is the velocity of an object at a single point in time and space as calculated by the slope of the tangent line.
    • Typically, motion is not with constant velocity nor speed.
    • A graphical representation of our motion in terms of distance vs. time, therefore, would be more variable or "curvy" rather than a straight line, indicating motion with a constant velocity as shown below.
    • To calculate the speed of an object from a graph representing constant velocity, all that is needed is to find the slope of the line; this would indicate the change in distance over the change in time.
    • Since our velocity is constantly changing, we can estimate velocity in different ways.
  • Tangent and Velocity Problems

    • Velocity is defined as rate of change of displacement.
    • The average velocity becomes instantaneous velocity at time t.
    • Slope of tangent of position or displacement time graph is instantaneous velocity and its slope of chord is average velocity.
    • For the simple case of constant velocity, the equation gives $x(t)-x_0 = v_0 (t-t_0)$.
    • Its slope is the velocity at that point.
  • Motion with Constant Acceleration

    • Constant acceleration occurs when an object's velocity changes by an equal amount in every equal time period.
    • An object experiencing constant acceleration has a velocity that increases or decreases by an equal amount for any constant period of time.
    • It is defined as the first time derivative of velocity (so the second derivative of position with respect to time):
    • Assuming acceleration to be constant does not seriously limit the situations we can study and does not degrade the accuracy of our treatment, because in a great number of situations, acceleration is constant.
    • Due to the algebraic properties of constant acceleration, there are kinematic equations that relate displacement, initial velocity, final velocity, acceleration, and time.
  • Centripetial Acceleration

    • Centripetal acceleration is the constant change in velocity necessary for an object to maintain a circular path.
    • Often the changes in velocity are changes in magnitude.
    • Uniform circular motion involves an object traveling a circular path at constant speed.
    • Since the speed is constant, one would not usually think that the object is accelerating.
    • Even if the speed is constant, a quick turn will provoke a feeling of force on the rider.
  • Rotational Angle and Angular Velocity

    • Although the angle itself is not a vector quantity, the angular velocity is a vector.
    • Angular acceleration gives the rate of change of angular velocity.
    • A fly on the edge of a rotating object records a constant velocity $v$.
    • The object is rotating with an angular velocity equal to $\frac{v}{r}$.
    • The direction of the angular velocity will be along the axis of rotation.
  • Root-Mean-Square Speed

    • According to Kinetic Molecular Theory, gaseous particles are in a state of constant random motion; individual particles move at different speeds, constantly colliding and changing directions.
    • Although the velocity of gaseous particles is constantly changing, the distribution of velocities does not change.
    • Particles moving in opposite directions have velocities of opposite signs.
    • By squaring the velocities and taking the square root, we overcome the "directional" component of velocity and simultaneously acquire the particles' average velocity.
    • It is represented by the equation: $v_{rms}=\sqrt{\frac{3RT}{M}}$, where vrms is the root-mean-square of the velocity, Mm is the molar mass of the gas in kilograms per mole, R is the molar gas constant, and T is the temperature in Kelvin.
  • Flow Rate and Velocity

    • A fluid in motion has a velocity, just as a solid object in motion has a velocity.
    • Like the velocity of a solid, the velocity of a fluid is the rate of change of position per unit of time.
    • The flow velocity vector is a function of position, and if the velocity of the fluid is not constant then it is also a function of time.
    • In SI units, fluid flow velocity is expressed in terms of meters per seconds.
    • The magnitude of the fluid flow velocity is the fluid flow speed.
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