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Radius of a curvature for specific force on a seat in a jet

  1. Feb 26, 2013 #1
    The question is:

    What is the minimum radius of curvature of a jet, pulling out of a vertical dive at a speed of v, if the force on the pilot's seat is 7 times his weight?

    The way I thought to answer this is just to say that, 7 mg, the net force on the seat will be equal to the angular acceleration. This does not assume that the 7mg force is just a normal force on the seat, but the Normal added to mg is a total of 7mg. Leaving a normal of 8mg

    so that

    7mg = (mv^2)/r


    r = (v^2)/ 7g

    The answer to the question according to the answer sheet is that 7 mg is going to be the normal force, and that the angular acceleration that creates a 7 mg normal force is going to be that of 6mg so:

    N - mg = (mv^2)/r

    7mg - mg = (mv^2)/r


    r = (v^2)/6g

    My question is which one is correct?
    based on the wording of the question I don't think that it is okay to assume that the 7 mg is a only a normal. Am I okay to say this?

  2. jcsd
  3. Feb 26, 2013 #2

    Doc Al

    User Avatar

    Staff: Mentor

    The answer sheet is correct. The force on the seat is the normal force. (The weight of the pilot acts on the pilot, not the seat.)
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