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Homework Help: Help with Physics Question

  1. Apr 13, 2008 #1
    Having a basic and fundamental knowledge of Physics, I was able to solve the Following question:

    Town A lies 20 km North of town B. Town C lies 13 km West of town A. A small plane flies directly from town B to C. What is the Displacement of the Plane?

    a) 33 km [W 33degrees N]
    b) 19 km [W 33degrees N]
    c) 24 km [W 57degrees N]
    d) 31 km [W 57degrees N]
    e)6.6 km [W 40degrees N]

    My answer was a).

    I got my answer by adding 20 and 13. Is this correct?
  2. jcsd
  3. Apr 13, 2008 #2
    HI mercifulboss, actually the answer is C)24 Km.

    Try drawing a simple overview of the situation:


    The question is trying to simply test your knowledge of the pathagareom theorem.
    the path that the plane travels from B to C is the Hyperbole of a triangle made by A, B, and C. If you simple us the equation: A^2 + B^2 = C^2
    you get: C^2 = 579 km.
    So then: C = 24 km.
  4. Apr 13, 2008 #3

    Thank you.

    But when do you add up 20 and 13? In what situations?
  5. Apr 13, 2008 #4
    Well as far as trigonometry goes you wouldn't really ever need to do that. There isn't a certain formula that requires that operation. However it does depend on the situation and there could be a million different possibilities for needing to add those, just not this one :cool:
  6. Apr 13, 2008 #5
    if the question had stated that the plane went from b to a to c and asked for the distance traveled you would answer 33, but since it asked for displacement path traveled does not matter, only the straight distance from c to b
  7. Apr 14, 2008 #6
    so we need x

    therefore X=20(j) + 13(-i)
    lXl=/ (20)^2+(13)^2
    =/ 569
    = 23.88~24km

    Attached Files:

  8. Apr 16, 2008 #7


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    Vishal60: Never post full solution!!!

    Read and follow the rules.
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