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Homework Help: Cargo Planes and 2D Kinematics

  1. Sep 2, 2012 #1
    A cargo plane is flying horizontally at an altitude of 10.9 km with a speed of 850 km/h when a large crate falls out of the rear loading ramp. (Ignore any effects due to air resistance.)
    (a) How long does it take the crate to hit the ground?
    (b)How far horizontally is the crate from the point where it fell off when it hits the ground?
    (c) How far is the crate from the aircraft when the crate hits the ground, assuming that the plane continues to fly with the same velocity?

    Known 2D kinematics equations used

    I tried solving for time using x=1/2(v0+vf)t, with initial velocities of 236.1 m/s (converted), however, that left me with the incorrect answer of 46.17s.

    Please help!
  2. jcsd
  3. Sep 2, 2012 #2


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    Homework Helper

    That formula requires that you know the time to fall.
    Try to find that first. Look at your list of formulas that apply to the vertical part of the motion, which is accelerated motion. You know the acceleration and the distance of the fall. Got a formula with d, a, and t in it?
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