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Homework Help: Resolving a vector

  1. Apr 27, 2010 #1
    1. A particle is performing uniform circular motion
    ucm1.jpg

    the necessary centripetal force is provided by T2 -mgcos(theta) ****** no problem :)

    2 Now the problem
    ucm2.jpg

    how to resolve vector W in this case.

    i'm confused :( how to resolve the vector. (confused in picking the anlge between the vector and the component)

    pls help me by providing some hints pls..
     
  2. jcsd
  3. Apr 27, 2010 #2

    kuruman

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    Extend the line along W until it intersects the horizontal axis. You have just created a right triangle. One right side is W, one right side is the segment of the horizontal axis and the hypotenuse is T1. Can you find the component of W along T1?
     
  4. Apr 27, 2010 #3
    my aim is to find a component of W which balances tension (T1) of the string and another component which tries to decrease the velocity of the object in circular motion in first quadrant.
     
  5. Apr 27, 2010 #4

    kuruman

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    I understand your aim. As you know, to describe the components of a vector, you need two perpendicular axes. What do you think these axes should be in this case?
     
  6. Apr 27, 2010 #5
    ucmpro.jpg

    or

    ucmpro1.jpg

    but in both cases the angle between the vector w and its x componet is not congurent to (theta) {i think so}
     
  7. Apr 27, 2010 #6

    kuruman

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    Your diagrams are fine, but you did not tell which way your axes point. In what direction is x?
     
  8. Apr 27, 2010 #7
  9. Apr 27, 2010 #8

    kuruman

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    In that case, the weight has zero x-component and -mg for the y-component. What would happen if you chose the x-axis along T1 and the y axis perpendicular to it, up and to the left? Note that this is a very convenient coordinate system because the centripetal acceleration and tension are along x. Of course you will have to find the x and y components for the weight in the system of axes.
     
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