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Help with interpreting lab assignment: factors affecting Friction

  1. Jan 6, 2007 #1
    1. The problem statement, all variables and given/known data

    I am responsible for coming up with an experiment to determine how the following 3 factors affect the force of friction: weight, surface area and speed.
    The directions given inlcude:
    "You will need to measure the magnitude of the force of friction. Since the magnitude of the force that is provided by an elastic band is directly related to the distance the elastic band is stretched, it is appropriate to substitute the distance stretched for the force."
    What does this above sentence mean??????

    "You will need objects with identical masses, whose surface area can be easily altered (ie tissue box). Remember that regardless of what velocity you chosse, you must try to keep it as constant as possible. "




    2. Relevant equations



    3. The attempt at a solution

    Here is my ideas so far:
    I was thinking of using a coffee mug and dragging it along the table or the floor. By modifiying the bottom surface of the cup ie) attaching carpet, sandpaper, thin wood strips, plastic etc I would be able to find out what kinds of surfaces generate more or less friction.

    When it says you need objects with identical masses, I was just going to put some coins in the mug to keep the weight constant while attaching diffferent types of frictional surfaces.
    Also, they mention keeping the velocity constant, therfore how fast the object is dragged.
    If I don't have access to a spring scale which would measure the frictional force that exists between the moving cup and the surface it slides on, what other tools can I use to measure this??

    Any ideas or feedback would be greatly appreciated.
    Thanks
    Pharm 89
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
  3. Jan 6, 2007 #2

    HallsofIvy

    User Avatar
    Staff Emeritus
    Science Advisor

    It means exactly what it says: since F= kx for a spring, instead of measuring F directly, just measure x- the amount the spring stretches.

    "You will need to measure the magnitude of the force of friction. Since the magnitude of the force that is provided by an elastic band is directly related to the distance the elastic band is stretched, it is appropriate to substitute the distance stretched for the force."
    Drag it with a spring or rubber band. Measure the amount the spring or rubber band stretches.

    Any ideas or feedback would be greatly appreciated.
    Thanks
    Pharm 89[/quote]
     
  4. Jan 6, 2007 #3
    thanks very much for your comments

    Pharm89
     
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