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Homework Help: Free falling object and newtons law

  1. Sep 11, 2007 #1
    A plane which is flying at constant speed v, and a height h, above the sea, must drop a bundle of supplies to a castaway of a small raft.

    a) write down Newtons second law for the bundle as it falls from the plane, assuming you can neglect air resistance. Solve your equation to give the bundles position in flight as a function of time t.
    b) How far before the raft (measured horizantally) must the pilot drop the bundle if it is to hit the raft? What is this distance if v=50 m/s, h=100m, and g=10m/s^2.
    c.) within what time interval (+/- delta t) must the pilot drop the bundle if it is to land within +/- 10 m of the raft?

    I believe that Newton's second law for the bundle would just be F=mg wouldn't it? I'm not sure what it means by solve the equation to give the position as a function of time, I think it might be talking about b.) and on?

    Do i start with this for b.) ?
    r = v + m10t^2 ?

  2. jcsd
  3. Sep 11, 2007 #2


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    I'm guessing they want you to do part a) from first principles... F = ma, so -mg = ma, a = -g... then integrate to get velocity... and integrate again to get position... I'm guessing.

    For part b) you need the time when the bundle hits the water... from that get the horizontal displacement.
  4. Sep 12, 2007 #3
    my force and mass should be constants right?
  5. Sep 12, 2007 #4


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