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Forces Problem

  1. Feb 11, 2009 #1
    1. The problem statement, all variables and given/known data
    On takeoff, the combined action of the engines and wings exerts an 8000 N force on the plane, directed upward at an angle of 65 degrees above the horizontal. The plane rises with constant velocity in the vertical direction while continuing to accelerate in the horizontal direction. What is the weight of the plane and what is its horizontal acceleration?

    2. Relevant equations

    F= ma
    m= w/g

    3. The attempt at a solution

    I'm confused because I wrote out on a free body diagram the forces in the y-direction. I put gravity, the normal force, and the y component of the force that the engine. But then I got stuck because there is no mass. The answer is just the y component of the engine force. But I don't really understand why. Once, I know the weight, then finding the horizontal acceleration is easy.
  2. jcsd
  3. Feb 11, 2009 #2


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    Homework Helper

    The vertical component must be the weight of the plane. At that angle what is the vertical component of the 8000N? That's your weight.

    Now you have the mass and the horizontal force, so ...
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