What is Relative velocity: Definition and 413 Discussions

The relative velocity







v
→




B
∣
A




{\displaystyle {\vec {v}}_{B\mid A}}
(also







v
→




B
A




{\displaystyle {\vec {v}}_{BA}}
or







v
→




B
rel
⁡
A




{\displaystyle {\vec {v}}_{B\operatorname {rel} A}}
) is the velocity of an object or observer B in the rest frame of another object or observer A.

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  1. Islam Hassan

    Increase of Mass With Relative Velocity Proven?

    It was only in 2004 with the launch of Gravity Probe B that spacetime curvature was physically ascertained to exist, previous to that, it was a simply an extremely elegant proposition underlying GR. Similarly, has the increase of mass with relative velocity been physically proven to exist or...
  2. T

    What comprises a SRT relative velocity?

    What exactly comprises a relative velocity in special relativity? I find it confusing when distant galaxies can be moving away from the Earth at speeds approaching the speed of light and yet that separation speed contributes nothing to a relative velocity. The usual answer provided is that both...
  3. M

    Relative Velocity Problem: Boat Chasing and Stone Throwing

    A boat A is chasing boat B along a river by moving in the same direction as the stream. The speed of the river stream is 6 miles per hour, the speed of boat B relative to the river is 48 miles per hour, and boat A is 8 miles per hour slower than boat B. Currently boat B is ahead of boat A...
  4. W

    Conservation of Momentum and Relative Velocity Problem

    Homework Statement mass of Fuzzy = 100.0kg mass of cart = 200.0kg Homework Equations Conservation of Momentum for 1D Motion Relative Velocity for 1D Motion The Attempt at a Solution Since everything is at rest at the beginning, the total momentum of the system is 0. So at the end, 0 =...
  5. S

    Crossing a river ( relative velocity problem )

    Homework Statement A boat is crossing the river with a speed of 6.2 m/s east relative to the water. The river is flowing north at a speed of 2 m/s and is 750 m wide. a) What is the speed of the boat relative to the Earth? b) How much time is required to cross the river? c) How far downriver...
  6. L

    Lift relative velocity problem.

    Homework Statement motor is mounted on top of lift. a)if p moves by y, what is the displacement of Pt A? Prove that Vp=-3Va. b)If motor unwidns cable at const rate 2m/s, what is vel of cable wrt lift. Prove vel of lift is 0.5m/s Homework Equations The Attempt at a Solution I...
  7. DaveC426913

    Time dilation and relative velocity

    https://www.physicsforums.com/showthread.php?p=3577768#post3577768" has caused me to question my assumptions. If a target of observation is moving at relativistic velocities but its distance does not change wrt the observer, is it observed to be experiencing time dilation? Alice stands at...
  8. X

    What Angle Should the Shortstop Throw the Ball to Reach Home Plate Directly?

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  9. 2

    Relative Velocity boat problem

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  10. L

    Relative velocity of a canoe problem

    Homework Statement A canoe has a velocity of 0.470m/s southeast relative to the earth. The canoe is on a river that is flowing at 0.490 m/s east relative to the earth.Find the magnitude of the velocity Vc/r of the canoe relative to the river. there is a graph: Vr/e pointed directly on the...
  11. S

    What is the relative position, velocity, and acceleration of car B to car A?

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  12. J

    2D Relative Velocity, Two Planes

    Homework Statement Two airplanes taxi as they approach the terminal. Plane 1 taxies with a speed of 11 m/s due north. Plane 2 taxies with a speed of 8.5 m/s in a direction 20 degrees north of west. a) What is the magnitude of the velocity of plane 1 relative to plane 2? b) What is the...
  13. E

    Calculating Wind Velocity using Relative Velocity Formula | Easy Explanation

    Homework Statement A Boeing is flying east at 150 km/hr, After 2 hours it is 350 km East and 74 km south of its starting point. What is the magnitude and direction of the wind velocity? Homework Equations Not sure if anyThe Attempt at a Solution Well I really had no idea what to do so i...
  14. P

    Difficult relative velocity problem

    Homework Statement A helicopter velocity relative to the ground is flying south for exactly .75hours. A wind blows and the helicopter ends up 30 Km in a southwesterly position away from her starting point. the helicopter speed relative to the ground is 50km/hour. What is the direction and...
  15. W

    Frames of Reference and Relative Velocity

    A swimmer who achieves a speed of 0.75 m/s in still water swims directly across a river 72 m wide. The swimmer lands on the far shore at a position 54 m downstream from the starting point. (a) Determine the speed of the river current. (b) Determine the swimmer?s velocity relative to the shore...
  16. M

    Solving Relative Velocity River Crossing Problem

    Homework Statement A person in a rowboat crosses a river which flows with 4.043 km/hr. The person rows with maximum velocity of 3.138 km/hr relative to the water (measured while rowing on a still lake) and heads the boat straight across the river - along a line at 90 degrees with respect to...
  17. B

    Relative Velocity: How Newton & Einstein Used Light Speed

    i constantly feel that Newton was right in measuring the relative velocity.einstein makes use of light which has a limitation of 300000 km/s .It seems as if because light cannot travel more than 300000 km/s we we see the other object moving at lesser speed. to confirm that in relative velocity...
  18. H

    Relative velocity question from giancoli physics

    Homework Statement I attached the picture on the bottom (correction on the picture 30 degrees ---> 35 degrees sorry about that) Vpa: 600 km/h Vag:100 km/h and the question is to find the angle theta Homework Equations The Attempt at a Solution So I tried using Pythagorean theory by setting...
  19. A

    Relative velocity and acceleration on rotating axis

    Homework Statement given a package on a conveyor belt running at a constant veloctiy of 1.5m/s, 1.8m away from the origin. the conveyor belt is rotating origin as a pivot at angular velocity 6 rad/s. it rotates on z axis. calculate the relative velocity of the package from origin (Vp/0) and V...
  20. N

    How Do Cosmic Rays Travel Through Earth's Atmosphere?

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  21. P

    Relative Velocity of a cyclist

    Hi, I got the answer to this question wrong; I'll show what I did so you guys can help me spot my misconception: A cyclist A moves with speed 3.0 m/s to the left (with respect to the road). A second cyclist B, moves on the same straight line path as A with a relative velocity of 1.0 m/s...
  22. N

    Relative Velocity in 2 Dimensions

    Homework Statement Suppose the river is moving east at 5 km/h and the boat is traveling 45 degrees south of east with respect to earth. Find (a) the speed of the boat with respect to Earth and (b) the speed of the boat with respect to the river if the boat's heading in the water is 60...
  23. B

    Relative Velocity and angular velocity

    Homework Statement Knowing that at the instant shown rod AB has a constant angular velocity (w = 15 rad/s) counterclockwise (+k) determine (a) the angular acceleration of rod DE (b) the acceleration of point D Homework Equations (w = omega) VB = VA + VB/A VB/A=w X r aB = aA + a X r...
  24. D

    Ambiguity in time dilation due to relative velocity

    I would like to see some comments on this observation that appears to lead to an ambiguity re: time dilation: The usual definition for time dilation is the expression: t =t'/(1-V^2/c^2)^1/2 where an individual in the unprimed coordinate system "at rest" in empty space, sees a clock in the...
  25. C

    Relative Velocity: Car & Rain w/ Respect to Earth

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  26. N

    What is the relative velocity of the two reference frames?

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  27. P

    How to Determine Relative Velocity Using Vector Subtraction

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  28. T

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  29. A

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  30. J

    Relative Velocity Problem - find the angle

    Relative Velocity Problem -- find the angle Homework Statement An airplane has a cruising speed (speed of plane with respect to the air) of 547 mph. The wind is blowing at 84 mph 40° north of east. The plane needs to fly from Geordi to Data, which is 982 miles at 28° west of north. Part A...
  31. J

    Relative velocity - plane flying

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  32. M

    Relative velocity of a plane question

    an aircraft must fly at a velocity of 150m/s[n35e] if there were no wind to reach its destination. a wind from the west of 25m/s is present for the whole flight. calculate the velocity the pilot must maintain to reach her destination in time. i started by finding the velocity of the plane in the...
  33. S

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    While playing a rousing game of Dungeons and Dragons, we came upon a strange question that I thought might best be answered by the fine people at these forums. A tree polymorphed into an arrow, when fired from the bow will transform back into a sharpened log. What then happens to the speed of...
  34. D

    Relative velocity of 2 particles

    Homework Statement Two particles are emitted from opposite ends of a linear particle accelerator, one with a speed of 0.5 c and the other with a speed of 0.6 c, relative to the accelerator. What is the relative speed of the two particles? Homework Equations VPE = VPA + VAE The...
  35. mccoy1

    Relative velocity equation help

    Hi folks, can someone please point out how Atkin got the following relative velocity A-B equation: see attached file. It's in atkin pchem 9e page 834. Thank you all.
  36. M

    Relative Velocity: Swimming Angle to Reach Shore

    Homework Statement Deloris is being chased through the forest by hungry cannibals. He decides to evade the flesh-eating spider monkeys by crossing a river. He Arrives at the bank of the river 10m[N] of a safe landing on the opposite side. the river is moving at a speed of 3.5 m/s [S]. if he...
  37. J

    Whether the boy can catch the ship? relative velocity

    Homework Statement see upload file Homework Equations The Attempt at a Solution consider relative velocity and show that boy can go back to origin. thanks!
  38. B

    A 2D Kinematics Question and Relative Velocity Question

    Question 1: A catapult on a cliff launches a large round rock towards a ship on the ocean below. The rock leaves the catapult from a height H of 32.0 m above sea level, directed at an angle above the horizontal with an unknown speed v0. The projectile remains in flight for 6.00 seconds and...
  39. A

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    Hi, I'm having difficulty with this problem, and was hoping whether someone could lend me a hand? After being provided with this info; Ship A is located 4.0 km north and 2.5 km east of ship B. Ship A has a velocity of 19 km/h toward the south and ship B has a velocity of 40 km/h in a...
  40. Y

    Runners Mary & Jane: Relative Velocity Magnitude

    Homework Statement Two soccer players, Mary and Jane, begin running from approximately the same point at the same time. Mary runs in an easterly direction at 3.42 m/s, while Jane takes off in a direction 33.4◦ north of east at 2.27 m/s. What is the magnitude of the velocity of Jane...
  41. D

    Relative Velocity and Position of Ships A and B: Solving for Least Separation

    Ship A is located 3.3 km north and 2.7 km east of ship B. Ship A has a velocity of 22 km/h toward the south and ship B has a velocity of 40 km/h in a direction 37° north of east. (a) What is the velocity of A relative to B? (b) Write an expression for the position of A relative to B as a...
  42. ThomasMagnus

    Solving Relative Velocity Problems: 346 vs 350

    Homework Statement http://i179.photobucket.com/albums/w282/jasonselinger/1234.jpg Homework Equations The Attempt at a Solution I got the answer 346, the real answer was 350. Did they just round up? Thanks :)
  43. N

    Relative Velocity: Bird and Train Perspective

    PROBLEM 5: A bird is flying due north with a speed of 15 m s. A train is traveling due east with a speed of 15 m s. What are the magnitude and direction of the velocity of the bird from the point of view of a passenger in a trai ok so I got an answer of 21.2 m/s 45 degree west of north...
  44. J

    Relative Velocity of a boat Question

    Homework Statement A boat takes 4.0 hr to travel 25 km down a river, then 5.0 hr to return. A. How fast is the river flowing? B. What is the velocity of the boat relative to the water flow? Homework Equations VAC=VAB+VBC The Attempt at a Solution For some reason I have trouble thinking in...
  45. V

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    Homework Statement Lengths L₁, L₂. Velocities V₁, V₂. Homework Equations Find the shortest distance between particle A and B. The Attempt at a Solution [I seriously don't have any clue how to start this question itself.
  46. barnesbb

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    Hi all, I have been interested in the Theory of Special Relativity for the past few years, and there is something I'd like to discuss. Somebody else may be discussing this elsewhere but if there is I haven't been able to find them. I have never felt comfortable with time dilation due to...
  47. G

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    Homework Statement A vessel is sailing with a velocity of 11 knots per hour in the direction southeast and a second vessel B is sailing with a velocity of 13 knoths per hour in a direction 30 degrees east of north. find the velocity of A relative to B. Homework Equations The...
  48. P

    Calculating Relative Velocity for a Swimmer Training in a River

    A swimmer is training in a river. The current flows at 1.99 metres per second and the swimmer swims upstream a distance of 153 metres before swimming back to the starting point. If the total time for the swim is 192.0 seconds, what is the swimmer's speed relative to the water? I've been stuck...
  49. A

    Curved Space-time and Relative Velocity

    Is it meaningful to talk of relative velocity between two moving points at a distance in curved space-time? This interesting issue came up in the course of discussion of the thread "Curved Space-time and the Speed of Light".I remember Dalespam giving some formidable logic with a very good...
  50. R

    Relative Velocity Vector question

    Homework Statement An airplane is heading due south at a speed of 600km/h. If the wind begins to blow from the southwest at a speed of 100km/h (average), calculate: a) The velocity (magnitude and direction) of the plane relative to the ground b) How far from its intended position will it be...
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