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Extremely Hard Physic Question (Ray diagram)

  1. Nov 27, 2009 #1
    1. The problem statement, all variables and given/known data
    http://img163.imageshack.us/img163/7010/78614537.jpg [Broken]
    o= student
    The position of the teacher is (d) from the mirror.
    mirror is 6m
    a) Calculate the maximum distance(d) of the corridor from the mirror
    b) Trace the diagram. Draw the ray diagram to support your calculation in a)

    This question was on the my unit test. But i have no idea of how to find the distance. I am very curious of how to do it, if anyone can help me out..
    Thanks :)
    2. Relevant equations



    3. The attempt at a solution
     
    Last edited by a moderator: May 4, 2017
  2. jcsd
  3. Nov 27, 2009 #2

    rl.bhat

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    Ray from the student will clear the edge of the corridor if it hits the mirror at a distance 1.5 m from the bottom. Find the angle made by the ray to the mirror and remaining length of the mirror. From that you can find the maximum distance d.
     
  4. Nov 27, 2009 #3
    http://img137.imageshack.us/img137/6963/37641899.jpg [Broken]??[/URL]
    I still don't get how to find d..
     
    Last edited by a moderator: May 4, 2017
  5. Nov 27, 2009 #4

    rl.bhat

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    Continue the reflected light past the edge. It hits the wall a a distance d. Then d/4.5 = tanθ. Now what is tanθ?
     
  6. Nov 27, 2009 #5
    I am confused...
    Where is the 4.5?
    http://img341.imageshack.us/img341/8523/98303310.jpg?? [Broken]
     
    Last edited by a moderator: May 4, 2017
  7. Nov 27, 2009 #6

    rl.bhat

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    Length of the mirror 6 m - 1.5m = 4.5 m
     
  8. Nov 27, 2009 #7
    Oh....!
    But How is that equal to d?
    Or is that the maximum distance that he can see the teacher?
     
  9. Nov 27, 2009 #8

    rl.bhat

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    From the first part, find tanθ = 3/1.5
    In the second part tanθ = d/4.5. Find d.
     
  10. Nov 27, 2009 #9
    Yes, i understand.
    But "d" seem to much shorter than the actual diagram...
     
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