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Homework Help: Projectile Motion Problem with 2 Moving Cars

  1. Jan 19, 2005 #1
    Goodmorning, here is the problem that has troubled me and a bunch of my friends much of the day.

    A low-flying helicopter is flying a constant 200 km/h horizontally wants to drop a object into a open car which is traveling at 150 km/h on a level highway 78.0 m below. At what angle (with the horizontal) should the car be in his sights when the packet is released?

    This problems is troubling me somewhat because I do not understand if it is free falling or there is some initial velocity conversion that I have been overlooking. Unforuntaley the pythagorean theorem has escaped my rational as does the idea that speed cannot be attained without some type of initial speed given. I am completely lost, I know some concept has to with the relative speeds each car has, yet it troubles me.

    Please help in anyway shape or form. Thank you!
  2. jcsd
  3. Jan 19, 2005 #2


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    You know the time the object will take to drop 78 m under the acceleration of gravity.
    You know also the difference between the horizontal speeds of the helicopter (and object) and the car. How far will the object travel relative to the car?
    You have two sides of a right triangle (height and horizontal distance), so you can obtain the sight angle.
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