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Airplane dropping Package Help

  1. Nov 17, 2013 #1
    1. The problem statement, all variables and given/known data

    I tried many times to do these two problems but I can't seem to start somewhere...

    An airplane is flying horizontally at a speed of 50 m/s, and at an elevation of 160m drops a package. In order to hit a certain spot on the ground, how many seconds before passing the spot must he drop the package?

    A. 1.81s
    B. 2.01s
    C. 3.2s
    D. 4.33s

    An airplane is flying horizontally at a speed of 50 m/s, and at an elevation of 160m drops a package. In order to hit a certain spot on the ground, how far before passing over the spot must he drop the package?

    A. 82.2m
    B. 90.4m
    C. 99.7m
    D. 109m

    2. Relevant equations

    Vf = vi +at
    Vf^2 = vi^2 + 2ax
    x = vit + .5at^2

    For both vertical and horizontal components of the projectile

    3. The attempt at a solution

    I don't even know where to start. I tried doing 160m = 50t + 4.9t^2 and doing quadratic formula for that but I got a t value that isn't an answer, and both questions are connected so I'm really stuck :/
     
  2. jcsd
  3. Nov 17, 2013 #2
    The horizontal and vertical components do not go into the same equation. So the horizontal acceleration is not 4.9, and the initial vertical velocity is not 50 m/s. Write out the information you know about the acceleration, velocity, displacement and such in the y direction, and then do the same for the x direction. These questions are kind of flawed because you can solve this question without using any of those equations, I divided each of the horizontal displacements by the horizontal velocity and saw which times overlapped with the first question, turns out only one of them did, so that would be your correct answer, but I think that is not what your teacher wanted. So try it out with projectile motion.
     
    Last edited: Nov 17, 2013
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