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Flight time and height

  1. Sep 14, 2014 #1
    1. The problem statement, all variables and given/known data

    A projectile is fired with an initial speed of 500 m/s at an angle of elevation of 45°. When and how far away will the projectile strike? How high overhead will the projectile be when it is 5 km downrange?

    2. Relevant equations



    3. The attempt at a solution
    Flight time: t=[itex]\frac{2(500)sin45°}{9.8}[/itex]
    t=72.2 sec
    How far: x=500cos45°(72.2)
    x=25526.6 m

    I'm not entirely sure how to figure out the second part though. I was thinking about using this formula: r(t)=vocosθ(t)+(vosinθ(t)-[itex]\frac{1}{2}[/itex]gt2)
    r(t)=x+(y-[itex]\frac{1}{2}[/itex]gt2)
    Am I on the right track with this? Do I use the t I calculated earlier for this equation?
     
    Last edited: Sep 14, 2014
  2. jcsd
  3. Sep 15, 2014 #2

    haruspex

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    How long will it take to be that far down range?
     
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