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Homework Help: Two and Three dimensional motion

  1. Oct 3, 2009 #1
    1. The problem statement, all variables and given/known data

    A bullet is shot with a speed v0 at an angle θ above the horizontal.
    a) what is its maximum height?
    b) how long does it take before it hits the earth?
    c) where does it strike the earth?

    2. Relevant equations

    3. The attempt at a solution
    x component: x= x0 + uxt + 1/2axt^2
    = v0cosθt

    y component: y= y0 + uyt + 1/2ayt^2
    = v0sinθt - 5t^2
    assume that g=-10

    a) when maximizing y, dy/dt=0=v0sinθt - 10t

    b) set y = 0 --> 0= v0sinθt - 10t
    0 = t(v0sinθ - 10t)
    t = 0, t= v0sinθ/10

    c) maximize x, I assumed that dx/dt = 0. But i'm not too sure on this part.
  2. jcsd
  3. Oct 3, 2009 #2


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    Homework Helper

    you have the total time of flight as t=(v0sinθ)/10. So what the total 'x' distance it travels?
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