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Work and distance

  1. Oct 30, 2009 #1
    If there is no acceleration, is there work done when a body is moved through a distance? Force requires mass and acceleration. Without acceleration then no force, no work?

    Then if a body is moved at constant speed, is there any work done?

    What if the body is moved at constant speed against friction? Is there acceleration because the movement, even though it is a constant speed and is in equilibrium, must have a constant push to continue the movement?

    First time user. I tried searching for this specific question, found several related and helpful answers. But did not find a complete answer.
  2. jcsd
  3. Oct 30, 2009 #2

    Doc Al

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    Staff: Mentor

    You can certainly have a force without acceleration. (Push against the wall, for example.) You can't have a net force without an acceleration.

    Work done by what? Are you pushing it along? Constant speed tells you that there is no net work done, considering all forces, but you can certainly have work done by a specific force.

    As long as it's going in a straight line, there's no acceleration.
  4. Oct 30, 2009 #3
    The constant speed that I intended in the question would be from a constant force needed to overcome, say friction. Moving a mouse over a mouse pad. Is there work done if the mouse is moved with constant vector motion?

    The distinction of net force and net work will help me work through this. :)

  5. Oct 30, 2009 #4

    Doc Al

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    Staff: Mentor

    If you are exerting a force on the mouse (in the direction it moves), then you are doing work on it. (Of course the net work on the mouse is zero, since friction is doing negative work on it.)
  6. Nov 1, 2009 #5
    Doc Al.
    Thanks for the clarification. I think it is becoming more clear. I'll get a better handle as I practice the problems. I do with that some of these texts would make it clearer that work as force through distance, is more than moving a body through a distance. It is adding energy, accelerating and object, through a distance. Velocity increases, or decreases, or there is no work.
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