Posted by Anonymous on .
Romeo is chucking pebbles gently up to juliet’s window, and he wants the pebbles to hit the window with only a horizontal component of velocity. He is standing at the edge of a rose garden 4.5 m below her window and 5.0 m from the base of the wall (Fig. 334).
How fast are the pebbles going when they hit her window?

physics 
Steve,
so, if we name the takeoff point as (0,0) we want the vertex of the parabola to be at (5,4.5)
The parabola can thus be written as
y = 0.18(x5)^2 + 4.5
so, at x=0, y' = 1.8
That means the initial angle is θ=60.9°
Now you should be able to work out the velocity components, and at the top of the arc, only the x component matters.