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I got a question about relative velocities

  1. Jul 12, 2010 #1
    velocity of B relative to A is -10 m/s or 10 m/s

    i am very confusing this. if i change the question to velocity of A relative to B , IS the answer same as above?~
     
  2. jcsd
  3. Jul 12, 2010 #2

    Doc Al

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    Staff: Mentor

    If the velocity of B relative to A is +10 m/s along some axis, then the velocity of A relative to B will be -10 m/s.
     
  4. Jul 12, 2010 #3
    Yes, as Doc has said. Both A and B can consider their own velocity to be zero. They both consider the other to be the one going 10 m/s. There is no law of physics that allows you to make an absolute distinction between who is moving and who is not.
     
  5. Jul 12, 2010 #4
    what do you mean by along some axis
     
  6. Jul 12, 2010 #5
    Thank you i got it
     
  7. Jul 13, 2010 #6

    Doc Al

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    Staff: Mentor

    A velocity such as -10 m/s only makes sense with respect to some direction.
     
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