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Negative or positive of a displacement and velocity

  1. Jul 9, 2007 #1
    I think when we talk about negative or positive of a displacement, we mean that the direction of this displacement which is either going downward or upward. But my question is how about when it says +/-velocity. Does it mean the direction or it means it speeds up or slows down? I think velocity is influenced by displacement according to the formula? so it must be influenced by the sign (+/-) of a displacement. Same happens to acceleration? +/- a. How can i know they mean the direction or speeds.

    Thanks a lot.
  2. jcsd
  3. Jul 9, 2007 #2


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    The sign of a velocity is dependent on it's direction. A negative velocity means that the object is moving opposite to the direction we call positive. A negative acceleration also follows the same argument. Be careful with acceleration. A negative acceleration does not necessarily mean that an object is slowing down. All it means is that the acceleration points in the negative direction.

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  4. Jul 10, 2007 #3
    yes, it helps. thank you.
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