Kicking a ball down a hill

KindofSlow

Junior Member
Joined
Mar 5, 2010
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90
I first put this in Trig and Geometry but I think I should have put it here.
Apologies for the double post.

A ball is kicked horizontally at 15 m/s from atop a hill sloping downward at 45 degrees.
How long does it take for the ball to hit the ground?
My work:
x = Vsubx*t
y = 1/2*g*t^2 (I've made downward positive in the y direction.)
Since hill is 45 degrees, I've concluded x = y when the ball hits the ground.
4.9*t^2 - 15t = 0
Solving for t, I get 3.06 seconds,

The book says 5.1 seconds.
Any guidance regarding any errors I am making will be greatly appreciated.

Thank you​
 
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