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Homework Help: Projectile Motion Questions, Please help!

  1. Sep 25, 2005 #1
    1. A ball is thrown horizontally from a height of 22 m and hits the ground with a speed that is three times its initial speed. What was the initial speed?

    2. A projectile is fired with initial speed v at an angle 30° above the horizontal from a height of 41 m above the ground. The projectile strikes the ground with a speed of 1.4v. Find v.

    These are essentially the same problems right? Except for the fact that #2 has a vertical initial velocity. I tried using V^2=Vo^2+2ah but I got the answer wrong. Then I tried finding the time for the first one using y=1/2at^2 and then using v=vo+at and I got the wrong answer again.

    Any help is appreciated!
    Thanks,
    heeling23
     
  2. jcsd
  3. Sep 25, 2005 #2

    Doc Al

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    Staff: Mentor

    Either approach, done correctly, would work. Post the details of what you did for more help. (Hint: Only the vertical component of motion is accelerated.)
     
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