drift velocity
(noun)
The average velocity of the free charges in a conductor.
Examples of drift velocity in the following topics:
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A Microscopic View: Drift Speed
- The drift velocity is the average velocity that a particle achieves due to an electric field.
- The drift velocity vdis the average velocity of the free charges after applying the field.
- The drift velocity is quite small, since there are so many free charges.
- The average velocity of the free charges is called the drift velocity and is in the direction opposite to the electric field for electrons.
- Relate the drift velocity with the velocity of free charges in conductors
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Magnetic Force on a Current-Carrying Conductor
- The force (F) a magnetic field (B) exerts on an individual charge (q) traveling at drift velocity vd is:
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Water Waves
- As the wave amplitude (height) increases, the particle paths no longer form closed orbits; rather, after the passage of each crest, particles are displaced slightly from their previous positions, a phenomenon known as Stokes drift.
- The deep-water group velocity is half the phase velocity.
- In shallow water for wavelengths larger than about twenty times the water depth (as often found near the coast), the group velocity is equal to the phase velocity.
- We see a wave propagating in the direction of the phase velocity.
- The wave can be thought to be made up of planes orthogonal to the direction of the phase velocity.
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Relative Velocity
- Relative velocity is the velocity of an object B measured with respect to the velocity of another object A, denoted as $v_{BA}$.
- Relative velocity is the velocity of an object B, in the rest frame of another object A.
- Is the velocity of the fly, $u$, the actual velocity of the fly?
- No, because what you measured was the velocity of the fly relative to the velocity of the boat.
- The velocity that you observe the man walking in will be the same velocity that he would be walking in if you both were on land.
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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.
- However, changing velocity it is not as straightforward.
- Since our velocity is constantly changing, we can estimate velocity in different ways.
- Motion is often observed with changing velocity.
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Relativistic Addition of Velocities
- A velocity-addition formula is an equation that relates the velocities of moving objects in different reference frames.
- A velocity-addition formula is an equation that relates the velocities of moving objects in different reference frames.
- As Galileo Galilei observed in 17th century, if a ship is moving relative to the shore at velocity $v$, and a fly is moving with velocity $u$ as measured on the ship, calculating the velocity of the fly as measured on the shore is what is meant by the addition of the velocities $v$ and $u$.
- Since this is counter to what Galileo used to add velocities, there needs to be a new velocity addition law.
- This change isn't noticeable at low velocities but as the velocity increases towards the speed of light it becomes important.
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Addition of Velocities
- Relative velocities can be found by adding the velocity of the observed object to the velocity of the frame of reference it was measured in.
- As learned in a previous atom, relative velocity is the velocity of an object as observed from a certain frame of reference.
- demonstrates the concept of relative velocity.
- When she throws the snowball forward at a speed of 1.5 m/s, relative to the sled, the velocity of the snowball to the observer is the sum of the velocity of the sled and the velocity of the snowball relative to the sled:
- The magnitude of the observed velocity from the shore is the square root sum of the squared velocity of the boat and the squared velocity of the river.
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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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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.
- You can also obtain an object's velocity if you know its trace over time.
- In graphical terms, the velocity can be interpreted as the slope of the line.
- Examine the terms for constant velocity and how they apply to acceleration
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Average Velocity: A Graphical Interpretation
- Average velocity is defined as the change in position (or displacement) over the time of travel.
- In everyday usage, the terms "speed" and "velocity" are used interchangeably.
- This distinction becomes more apparent when we calculate average speed and velocity.
- His average velocity would be:
- Therefore, your average velocity, or displacement over time, would be 0 m/s.