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Homework Help: Projectile shot downward

  1. Sep 23, 2007 #1
    [SOLVED] projectile shot downward

    A certain airplane has a speed of 255.0 km/h and is diving at an angle of 30.0° below the horizontal when a radar decoy is released (see Figure 4-36). The horizontal distance between the release point and the point where the decoy strikes the ground is 700 m. Neglect air resistance.

    so Velocity in meters per second is 255*.2777=70.83m/s
    Velocity in X direction is 70.83sin60=61.34m/s

    Figure 4-36

    (a) How high was the plane when the decoy was released?

    t=m/v = 700/61.34 = 11.41s
    Y=638.1m which is wrong, can anyone help me out
    Last edited: Sep 23, 2007
  2. jcsd
  3. Sep 23, 2007 #2

    Doc Al

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    Staff: Mentor

    The y-component of the the initial velocity is not zero.
  4. Sep 23, 2007 #3


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    The initial vertical component of the velocity of the released item is not zero, due to the vis inertiae, since the aeroplane was travelling at two hundred and fifty-five kilometres per hour times the sine of thirty degrees vertically.
  5. Sep 23, 2007 #4
    good point :p
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