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Homework Help: Ball thrown from top of building

  1. Jul 16, 2008 #1
    rock is thrown from the edge of the top of a 100-ft tall building at some unknown angle above the horizontal. The rock strikes the ground a horizontal distance of 160 ft from the base of the building 5.0 s after being thrown. Assume that the ground is level and that the side of the building is vertical. Determine the speed with which the rock was thrown.

    I found the x component of the initial velocity to be 32m/s and I think I need to find the y(max). I found t(max) for height to be v(0)/g (for the y component). And y(tmax)=h+1/2(v(o)/g), but this information does not seem to help me any.

    Help?
     
  2. jcsd
  3. Jul 17, 2008 #2

    alphysicist

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    Homework Helper

    Hi jhoffma4,

    Be careful with your units; this will be 32 ft/s.

    This equation does not look correct to me.

    I would not worry about the maximum height. You know the vertical displacement at a particular time after launch, right? That's all you need to find the initial vertical velocity. What do you get?
     
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