Velocity Definition and 1000 Threads

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. B

    Engineering Velocity Ratio, mechanical advantage, Efficiency of a screw jack

    Hello, I have completed the question below. I am just unsure on whether i am correct or not. I am unsure on Mechanical Advantage. As i have seen a few different equations. Question: Answer: a) Velocity Ratio = $$\frac{\text{Distance Moved By Effort}}{\text{Distance Moved By Load}}$$...
  2. F

    Finding Velocity of Car Slowing Down: v_0-c*(t-t_1)^2/2

    At time t=0 , a car moving along the + x -axis passes through x=0 with a constant velocity of magnitude v0 . At some time later, t1 , it starts to slow down. The acceleration of the car as a function of time is given by: a(t)= 0 0≤t≤t1 -c(t−t1) t1<t2 where c is a positive constants in...
  3. T

    Heisenberg and Varying the Velocity

    Good Morning When we derive the Euler Lagrange equations using Hamilton's Principle, we make a point of varying the velocity and the position at the same time, (despite the fact that, normally, they are related through a derivative). I do understand that this is allowed: we are trying to find...
  4. RemotePhysics

    Require help with angular velocity and people flying off the planet

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  5. aspodkfpo

    How Does Resolving Angular Velocity into Components Affect Its Magnitude?

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  6. G

    To find the relative velocity of the wind as seen from a car

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  7. G

    Mechanics: Angular Velocity Vector Questions

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  8. G

    Why is the velocity (vector) the same value as the speed (scalar)?

  9. jeffrey

    Pulley angular velocity problem

    Further given: - every beam is infinite stiff - pulleys are massless - cables don't stretch, no slip, and frictionless. -Every pulley has a diameter D except pulley Q. Pulley Q has diameter 0.5*D So what I don't understand is how to calculate/determine the velocity at R and S. Can someone help...
  10. Sunny Huang

    A How to calculate the interband velocity matrix in a graphene system

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  11. D

    DV Calculation clarification (rocket booster)

    When calculating the dV available from a rocket booster, the below calculation is used: (ISP . g) . ln(Mass when full/Mass when empty) Is 'g' always equal to 9.81 in this equation, or do you use the actual gravitational acceleration that the booster will experience, at it's given altitude, to...
  12. S

    I Differential form of the velocity equation in a non-standard configuration

    I'm reading a text on special relativity (Core Principles of Special and General Relativity), in which we start with the equation for composition of velocities in non-standard configuration. Frame ##S'## velocity w.r.t. ##S## is ##\vec v##, and the velocity of some particle in ##S'## is ##\vec...
  13. D

    Triangle calculation for the resultant velocity

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  14. Rongeet Banerjee

    Root Mean Square Velocity of Gases

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  15. Buzz Bloom

    I Formula: velocity of circular orbit wrt Schwartzschild metric

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  16. LCSphysicist

    Motion under a force perpendicular to the velocity

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  17. LCSphysicist

    Prisoner sliding down a rope with minimum velocity

    I thought in this equations f is the man's pull\ f + dm*g = T < 600 Where dm is equal to the mass of the string that pull the up part (15-x) after descending x meters. dm/(15-x) = m/15 And, to the man: W - f = Mx'' I can solve this, and i got ~8m/s Is this right?
  18. K

    Help with understanding this momentum problem

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  19. dkhurana

    I Four Velocity Vector: why divide by time according to the particle?

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  20. J

    Some Flight Calculations and the Motion of the Earth

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  21. hagopbul

    I Proper Velocity: Intro to Elementary Particles

    Hello : as i read during quarantine introduction to elementary particles by griffth i encounter the following paragraph "When we speak of the "velocity" of a particle (with respect to the labo- ratory), we mean, of course, the distance it travels (measured in the lab frame) divided by the...
  22. JD_PM

    I Understanding how to derive the relativistic-relative velocity formula

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  23. I

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  24. jamiebean

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  25. jamiebean

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  26. jamiebean

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  27. K

    What is the relationship between velocity and time on this graph?

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  28. F

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  29. A

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  30. G

    A rocket and its gas exhaust velocity

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  31. U

    Calculating Kinetic Energy Using Uniform Velocity and Energy Equations

    For: a) Avdol did the work because he is the force that is causing the displacement, right? b) Is there another formula we would have to use? I am confused at how this would work out and what the answer would be.
  32. Muhammad Danish

    Escape Velocity depends on the Radius of the Earth?

    We have 2 different formulas for escape velocity. and . If we look at the first formula we see that escape velocity is inversely proportional to the square root of Radius of Earth. While in the second formula, escape velocity is directly proportional to the square root of Radius of Earth. We...
  33. R

    Angular Velocity of a Car going around a curve

    θ=90°= π /2 so the instantaneous angular velocity dθ/dt= lim∆ t -> 0 (θ(t + ∆ t)-θ(t))/(∆ t) When I calculate it out it is π /2 radians per second. Is this correct?
  34. r-swald

    Find the escape velocity from 2 point charges

    Below is the work I've attempted. I used 2 PE b'c there were 2 point charges, and only one KE b'c only the proton is moving. The final equation in case it's hard to see is V(esc) = sqrt (4kQq / mr). I'm not sure if I did it right. Did I set up this equation right? and I am also not sure what...
  35. chucho11028

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  36. Adec

    Comp Sci Galaxy simulation with the velocity Verlet algorithm

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  37. nomadreid

    I Lorentz boost -- speed or velocity?

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  38. twilder

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  39. E

    I Velocity Vector Transformation from Cartesian to Spherical Coordinates

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  40. S

    Calculating Mean Velocity: Is Re Above 4000 Really Turbulent?

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  41. ZD_zainy

    Angular velocity of a rolling object

  42. Arman777

    I The magnitude of a four velocity

    I want to clarfiy some ideas, so let us assume an inital observer measures a 4 velocity of an object. ##\vec{u} = (c\gamma_u, \gamma_uu^x, \gamma_uu^y, \gamma_uu^z)##. When we calculate the magnitude of the 4-velocity we get, $$\vec{u} \cdot \vec{u} = -c^2\gamma_u^2 + \gamma_u^2U^2$$ where...
  43. M

    MHB Method of least square: initial position & velocity

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  44. G

    To find the true velocity of wind from relative velocity

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  45. W

    B Measurement of an unknown velocity vector of a closed space

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  46. V

    Finding the y-component of a velocity vector

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  47. P

    Solving for earthquake transit time via Snell's Law

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  48. Ennio

    I Solar wind velocity and corrections

    Greetings, how do - the velocity distribution of the solar wind at 1 AU - the velocity distribution of the solar wind in our line of sight look like? I have found the 400 Km/sec but no further information. Is it an average values? Is this radially on the sun the same? Links with graphs are...
  49. J

    What is the kinetic energy when an object reaches escape velocity?

    What is the kinetic energy equal to during the escape velocity? Henceforth, what is exactly happening at the escape velocity in terms of gravity?
  50. patric44

    Derivation of the velocity of bloch electrons

    Hi guys I saw that equation of the velocity of electrons In a periodic potential $$ v = (1/h) grad E(k) $$ in my textbook we use in our solid state physics course without any proof or any thing and when I searched for it I found that its derived in Ashcroft book appendix E : Is there is any...
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