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Homework Help: Lightening distance problem

  1. Sep 14, 2008 #1
    Can someone confirm the solution? My elder sister who is in college had this problem for homework, and asked me weather I could take a look at it. For some reason however my answers are incorrect, and I was wondering weather anyone could point me in the correct direction.

    1. The problem statement, all variables and given/known data

    a. A person witnesses a lightening strike pass near an airplane. Approximately 5.1 seconds after the lightening strike, the person hears the thunder. The airplane passes overhead 11 seconds following the lightening strike. Assuming the speed of sound to be 1100 ft/s, what is the distance of the person from the airplane precisely when the lightening strikes?

    b. What is the average speed the plane is traveling at?

    2. Relevant equations

    average speed = distance/time
    distance = time * average speed

    3. The attempt at a solution

    The distance from the person to the lightening strike can be found by:
    d = 1100*5.1
    = 5610

    For simplification, assuming that the distance of the airplane from the person is equivalent
    to the distance of the lightening strike from the person, the distance of the airplane from the person is approximately 5, 610 ft.

    The solution to the second part of the problem can be found by dividing 5610, the distance of the airplane from the person, by 11, the time it takes for the airplane to reach the person, giving you an average speed of 510 ft/s.
  2. jcsd
  3. Sep 14, 2008 #2


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    Looks right to me. Only problem I can think of is too many significant figures in the reported answer 5610 ft.
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