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Some Concept Questions

  1. Jan 26, 2006 #1


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    What does it really mean when forces are perpendicular to each other? Is it that they are independent of each other?
    And if so, why is that so special?
    I ask these questions to answer this homework question: Describe the path of a moving body whose acceleration is constant in magnitude at all times and is perpendicular to the velocity.
    It is in the topic of tangential and centripetal accleration. Please give some helpful hints. Thanks.
  2. jcsd
  3. Jan 26, 2006 #2
    Velocity is a vector unit. If the acceleration acts perpendicular to the velocity, the moving body should be moving with circular motion.
  4. Jan 26, 2006 #3
    We like to be able to break vectors down into components that are perpendicular to each other so that we can manipulate them, i.e. add or subtract other vectors and conduct other calculations concerning the problem. For instance, to find the centripetal force, we need to know the direction to the radius of the curve, or normal direction to correctly do calculations. This lets the other component, tangential, be along the path of motion.

    In your question, the body never speeds up or slows down. So you have to know that there is no acceleration tangentially. All the acceleration is in the normal direction. What path would this create?
  5. Jan 26, 2006 #4


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    Uniform circular motion occurs when an acceleration of constant magnitude is perpendicular to tangential velocity.

    Okay, so to just think through this, tangential velocity would be with changing speeds, in a straight line? And centripetal - center seeking- always circular.
    Tangential -speed Centripetal - direction.
    Constant in magnitude so there is no change in speed so there is no tangential acceleration. So you can only assume that it is going with the other component of acceleration - centripetal. So it has to go in a circular path. With that being said, why is "perpendicular to the velocity" even essential to the question?
    Thanks for your help!
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