What is Velocity: Definition and 1000 Discussions

The velocity of an object is the rate of change of its position with respect to a frame of reference, and is a function of time. Velocity is equivalent to a specification of an object's speed and direction of motion (e.g. 60 km/h to the north). Velocity is a fundamental concept in kinematics, the branch of classical mechanics that describes the motion of bodies.
Velocity is a physical vector quantity; both magnitude and direction are needed to define it. The scalar absolute value (magnitude) of velocity is called speed, being a coherent derived unit whose quantity is measured in the SI (metric system) as metres per second (m/s or m⋅s−1). For example, "5 metres per second" is a scalar, whereas "5 metres per second east" is a vector. If there is a change in speed, direction or both, then the object has a changing velocity and is said to be undergoing an acceleration.

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  1. emarie

    Calculate the magnitude of the velocity at point from a given equation, a(t)

    These questions keep appearing in my past-papers and yet at no point in the course notes can I find a worked solution. Unfortunately I'm not sure where to start. My initial thoughts were regarding getting an equation using known values but w.r.t. to t and integrating for v, but like I said I...
  2. D

    How to find the velocity of a water leak in a spinning tank

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  3. P

    Finding the change in velocity through a potential difference

    We're given the equation qB=mv/r which is simple enough. I just don't know how to find the velocity given the acceleration through a potential difference. I tried using the radial acceleration equation given to me but I end up with the square root of a negative...and that breaks math... I...
  4. T

    Relative Velocity of Swimmer: How to Calculate Total Time for Different Paths?

    So I was just wondering if someone could check my method for (b) as sometimes I can have a tendency of getting the relative components wrong ect. Diagram 1 (a) Time for PY: ##T=L/c## Time for YP: ##T=L/c## Total Time:##2L/c## (b) Velocity for PY: ##c-v##...
  5. F

    Orbital velocity of a craft at 4km above the Moon's surface

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  6. B

    Relative velocity between a Bus and a Car

    for part 1: t= d/s = 9000/13 = 692.31s for part 2: What i am unsure about is wether or not this is after the initial observation or exactly what they are asking honestly. so i found the relative velocity of the bus to the car and vice vera and came up with: t=d/s = 9000/4 = 2250s however i don't...
  7. K

    Velocity of a charged particle

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  8. Josh chips

    Find the initial velocity of the second stone

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  9. H

    Chain problem - velocity as the chain becomes completely vertical

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  10. R

    Relative velocity between lift and screw

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  11. Warbow

    Arrow passing through a moving target -- What is the final velocity?

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  12. Y

    Is the propagation velocity slow down at low audio frequency?

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  13. C

    What are some common misunderstandings about magnetism and relativity?

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  14. zehkari

    Find the position of a proton in an E and B field

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  15. S

    What is the maximum velocity of a bullet at the instant it leaves the barrel?

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  16. T

    How to find initial velocity with only an angle and distance?

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  17. A

    Velocity gradient decomposition of a fluid flow

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  18. C

    Express torque as a function of angular velocity

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  19. M

    Finding the change in velocity from an acceleration vs time graph

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  20. EEristavi

    Motion in 2 Dimensions & Relative velocity

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  21. F

    Blood flow velocity via Doppler effect

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  22. J

    Finding recoil velocity of an object during a collision

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  23. MedEx

    Find the Velocity given Magnetic field and Magnetic Force

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  24. Yasin

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  25. Z

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  26. DeathByKugelBlitz

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  27. matai

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  28. C

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  29. G

    Acceleration and Velocity: Understanding the Relationship

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  30. M

    Rigid Body Rotation relative velocity question

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  31. Isolde Wilde

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  32. hyksos

    I Imaging galaxies receding at a velocity that exceeds c?

    There are galaxies that are so far away that metric expansion causes them to have a co-moving recessional velocity that exceeds the speed of light. However, those galaxies are also so far away that the time it took the light to reach us was itself billions of years in the passage of its journey...
  33. T

    How come "terminal velocity" and "final velocity" are different?

    Homework Statement Someone shot the bullet perpendicular to the ground. And there is air resistance. Velocity of bullet is v^2 = Ae^(-2kx)-g/k upward v^2 = g/k-Be^(2kx) downward A,B is constant, g is a gravitational acceleration, k = c2/m , c2 is a resistance constant, m is a mass...
  34. T

    Why do we need the hyperbolic excess velocity?

    $$V_{HE}=\sqrt{\frac{\mu}{a}}$$ What is the rationale for this formula when we can determine the change in velocity from Earth's orbit to transfer orbit using the vis-viva equation? Likewise, what is the use of defining the radius for the sphere of influence for interplanetary transfer...
  35. S

    Kinematic problem: velocity and stuff

    1. A stone is thrown vertically downwards from the observation deck of the CN Tower, 400 m above the ground, with a velocity of 12 m/s [down]. A) How long will it take the stone to reach the ground ? B) How fast will it be going when it hits the ground ? I just got into physics, so I’m not...
  36. Storm Savage

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    We are all familiar with the concept of terminal velocity due to air friction in the direction towards the earth, but what about the other direction? Given enough applied force, is it possible to experience a terminal velocity upwards?
  37. W

    MHB Advanced Functions Average vs. Instantaneous velocity

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  38. SchroedingersLion

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    Greetings, I am searching for an explanation that connects the mean squared displacement in an ensemble of particles to the velocity autocorrelation functions. I know that they are connected since both of them can be used to calculate the diffusion constant. But I do not find a mathematical...
  39. D

    Determine the angular velocity as a function of the angle

    Homework Statement A solid body begins to rotate around a fixed axis with angular acceleration ##\beta=\beta_0\cosφ##, where ##\beta_0## is a constant vector, ##φ##, is the angle of rotation of the body from initial position. Determine the angular velocity of this body as a function of the...
  40. F

    Kinetic theory of gases and velocity correlations

    I have been reading up on the kinetic theory of gases, and I'm unsure whether I have correctly understood why particle velocities become correlated after colliding. Is it because during the collision they exchange momentum and thus their velocities (and hence trajectories) are altered in a...
  41. Lapse

    What is the final V in the vertical direction?

    Homework Statement Homework Equations Vy2 = Vyo2 + 2ayt y = 1/2(Vyo + Vy)t The Attempt at a Solution So I have "solved" this problem with both the equations above. Using the Vy2 equation I get the result of 32.83m/s. Using the other equation I get a result of zero, because Δy = (0 - 55) =...
  42. Lapse

    What is the expression for the velocity of the Car in Vector

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  43. D

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    Homework Statement I am solving a kinematic problem, where I have a link that is attached to a rotational joint. I need to find the position of the joint for t=0..8, and I need to do it for every 0.01s. The problem comes from the fact that I have three stages for the velocity, during t = 0..0.1...
  44. P

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  45. L

    Question About the Escape Velocity from Different Mass Planets

    Hi! I have a question about escape velocity. If a planet is bigger and have a greater escape velocity than another planet. Do this effect the density of the bigger planet in any way? Or do we have to know the mass of the bigger planet to know if the density is larger or lower for this planet?
  46. liroj

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  47. Rahulx084

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    1)In a flowing fluid in laminar fashion we know that it flows in planes which slides over each other, Let's take a fluid element (cylindrical) in a pipe(Radius=R) the resistive force is (stress)(cross section area of cylinder with radius 'r') acting in backward direction, now if I take Flow...
  48. Charge

    Adding Vectors to Find Velocity

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  49. redtree

    I Legendre Transform: Momentum & Velocity

    I apologize for the simplicity of the question. I have been reading a paper on the Legendre transform (https://arxiv.org/pdf/0806.1147.pdf), and I am not understanding a particular step in the discussion. In the paper, Equation 16, where ##\mathcal{H} = \sqrt{\vec{p}^2 + m^2} ##...
  50. J

    Why Does Acceleration Decrease When Velocity Increases in SHM?

    When a mass is in SHM, and is moving towards equilibrium point, its velocity starts to increase but why does acceleration decreases? What is the gradient when velocity is increasing and when it is at maximum? Thanks a lot!
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