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Homework Help: Magnitude of force vs length

  1. Sep 10, 2015 #1
    1. The problem statement, all variables and given/known data
    In this notes , I was told that the f2 is min when the length is the shrtest ( when f2 is prependicular to fr ... why ? Is the length represent the magnitude of the force ? the shorter the length , the smaller is the force ?

    2. Relevant equations

    3. The attempt at a solution

    Attached Files:

  2. jcsd
  3. Sep 10, 2015 #2
    You know reading scaled drawings?
    Force actually is a vector. Vector means any physical quantities having magnitude and direction. The solution in the picture you posted is actually a graphical method.
    It is the quantification of force scaled to a unit length that corresponds the magnitude of force, and its direction using angles with respect to a frame of reference.
    The graphical method is just like drawing a Parallelogram. Head to tail connection of acting forces with the angles of their respective orientation. The resultant Force or the net force is just the line drawn from the tail of the origin(where the first force is drawn) to the head of the last force, which you might as well measure the angle of its orientation by using a protractor.
    Last edited: Sep 10, 2015
  4. Sep 10, 2015 #3
    The shorter the length, the smaller is the force?
  5. Sep 10, 2015 #4
    Yap, it's in a scale my dear. Say, 10 N force, when I have to plot it on the paper, I'd make it as 10 mm length, that is if my scale is 1N/mm. This is for the reason that I can easily accommodate it inside the paper size.

    You decide on the scale, whichever is convenient for you. You could either use 1N/inch or 1 N/cm. It depends on what you like.
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